Could the Spell Mastery ability Tethered Magic (HoH:TL, page 100) help?
actually if you have a intangible tunnel to the room you can cast an InIm on the room itself, and thus see the sword. It is jumping from the person to the room that is the trick.
my thoughts process is as follows- if the air in the room can be used as an arcane connection to the room, and your person in teh room is breathing that air, you could teleport the air from his lungs (ReCo(au) ) into a bottle and then use that arcane connection to establish an intangible tunnel to the room.
Also the final part is tricky: even if you can sense the sword, how do you target it, now that Ken reminded us that T: Sight is not an option? You can cast spells on the room, and the sword may be "part" of the room, but Room and Part are different targets anyway.
Not that I would have any problem with that anyway: I personally wouldn't mind that just adding an extra magnitude for effect complexity (which is what T: Part does, also) would be enough to do the trick. Something like...
Would that work for you?
And if not, what about a breakthrough to be able to add R: Part to other ranges, so you can target parts of Rooms, Structures and Boundaries?
The problems of that spell are on one side that it somehow detects swords without neither In nor Te requisites, and on the other that also lacks something to cut the effect just to the swords: think that a spell which just makes a whole room glow in pink would be exactly like that one in level an parameters.
I see now, thank you.
I realized I've been missing a crucial part of all the issue: the usage of the tunnel with the T:Room does indeed allow the Magus to target (or rather: to be "touching") the entire Room, but the primary target is still the Grog, and therefore she cannot consider the sword as a Part of the grog, if he is not carrying it. Jumping through the air of the room could then allow to switch the target from the Grog to the physical room itself (as opposed to a T:Room concept). It's maybe a little stretched, but I can work from that I guess, and I'm in a better place than before 
The spell you're describing is somehow what I was trying to accomplish, but I don't think it would be accepted in that form (we, as a troupe, tend to adhere to rather strict guidelines). It would be more likely to be accepted with a breakthrough.
The problems of that spell are on one side that it somehow detects swords without neither In nor Te requisites, and on the other that also lacks something to cut the effect just to the swords: think that a spell which just makes a whole room glow in pink would be exactly like that one in level an parameters.
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If that's all that prevents this spell from working, I have no problem adding a +1 magnitude for complexity, or a In/Te requisite.
But I've been thinking about this some more and I thought about an other solution, that lets you get a tunnel to the specific sword you are looking for (to cast subsequent spell through it).
First, let's create a tunnel to the man in the room next to the sword, like before.
Then...
Creating the tunnels ReVi General
R:Touch, D: Sun, T: Room
Creates one mystical conduit with each and every object within the room, that allows using spells of level up to the level of this spell.
(General, +1 Touch, +2 Sun, +2 room )
Now the caster has a bunch of tunnels opened. They all are the same, so it needs some sorting.
Inspecting the object InTe 10
R:Touch, D: Conc, T: Ind
See an object and its surroundings
Base 4, +1 Touch, +1 Conc, Ind
Unravelling the fabric of vim (appropriate level)
The caster just needs to cast the InTe spell on each tunnel one by one and close them with the PeVi spell until the only tunnel that remains is the one linked to the item he is looking for. If the InTe fails, it probably means the target is not valid (Corpus, Animal or other Form target) and the tunnel can also be dispelled. This could take quite some time, depending on the number of items in the room, hence the extended duration for the ReVi spell.
If you cast a CrCo spell with target room it heals people in the room, not the room itself. The people do not have to be "part" of the room, because the target room does not work the same as target:individual.
The base guideline is "create conduit or container for spells" not requiring the target of an individual- so anything in the room which was the target has a conduit you can cast through individually- it does not have to be part of the room.
Which brings up some really scary possibilities for using larger targets (structure for example) and a shorter range- you could create a conduit to everyone in a building within sight range with no ritual or arcane connection...
So once you have a conduit to a room, everything in the room is essentially touch range.
In terms of what was just posted, I believe creating the conduit with target room creates one conduit that covers the entire room and its contents, not hundreds of different conduits. Of course once you do that you could create a conduit to something in the room so you still have a conduit to it if it should leave the room...
I was just about to comment on that, I agree on what you are saying. There's still the issue of not being able to single out a specific object, but maybe it could be stretched to allow the T:Group, once you have the T:Room in place (allowing the Magus to mantain a tunnel to object brought outside the room after the spell casting)
This one does not open a bunch of tunnels, but just one tunnel to everything in the room.
This one inspects the original target. Granted, it could be used to detect the sword if the Grog is still carrying it, but again, it's not enough to make it a valid target for a direct spell.
There may be one relatively simple approach to Eufemia's problem - provided I have understood the real one, and it is not a stand-in for something quite different. Is this really a rules problem that came up in game, and thus needs to be solved while the magi are planning what to do with a grog at the end of an Intangible Tunnel?
Would Eufemia's troupe accept a group made up from different Hermetic Forms as a valid T: Group? This comes up often with a magus and his familiar, but could also be a grog and his stuff. Typically this is accepted after some dithering, because otherwise
makes little sense. If your troupe accepts this, targeting the grog through the Intangible Tunnel allows also to target the grog and his stuff as a T: Group. Yes, this still requires tailored spells with several Forms as requisites and the expensive group target, but it does not lead to decades of research projects.
It will still require a very capable spontaneous caster or the grog at the end of the Intangible Tunnel might die of boredom or thirst before the spells are available, though.
Cheers
The issue is a simplified case of a specific actual situation. My intention here is to establish a common ground for something that will reasonably come up often in our saga.
This is the actual context, anyway:
A Companion of the Maga has struck a bargain with a disguised demon. The sword is what she bargained for, and it's giving her everything bad you can imagine could come from a demonic tainted object
The Companion is currently sailing on a ship, raiding the Mediterranean Sea as a bloodthirsty pirate.
The Maga wants to
- Protect the Companion (they're also blood related)
- Recover the sword in order to investigate on it
- Track the demon and banish him for good
She is constrained in her options: she is a freshly gauntleted maga, in a Spring Covenant, with very limited mondane and arcane resources.
Having said that, I'm not entirely confortable with the T:Group on different Hermetic Forms, but again I could also work on that I guess.
Maybe she won't be able to solve the problem as she would have liked it. Not every problem has to have an easy solution
In that specific case, the Maga could attempt the following with standard spells, without Original Research, and with perhaps some help of her sodales:
(1) Cast the Intangible Tunnel on her companion, who might not be able to resist.
(2) Cast the simple HP p.84 InIm 5 Fingers for Eyes through the Intangible Tunnel to perceive the room he is in, and thus see the demonic sword.
(3) Cast an ArM5 p.135 ReCo 20 R: Touch D: Diam Strings of the Ănwilling Marionette through the Intangible Tunnel on her companion, who might not be able to resist.
(4) Cause that companion with this spell to grab his 'preciousss' demonic sword firmly.
(5) Cast an ArM5 p.135 ReCo 35 R: Touch Seven League Stride or ReCo 40 R: Touch The Leap of Homecoming through the Intangible Tunnel on her companion, who might not be able to resist, and thus bring him and the sword into her covenant's council chamber. To sort out casting requisites, read with your troupe:
(6) Take care of companion and sword in her covenant.
Cheers
Just to add: get the grog to take an AC to the room before you teleport them, so you can send them back to the same spot.
The problem is that while the conduit makes the grog range: touch it does not make what the grog is touching range:touch.
The sequence you are suggesting (spells at #5) is beyond the Covenant means, for the time being. In addition to that, it's not something that can be achieved on the spot, without at least a season of work (to purchase or borrow a lab text, for example). But yes, that would definetely work. I am just a bit reluctant to pursue the teleportation route, but this is mostly due to how we (troupe) are choosing to portray magic in our saga. It could be done, but it's not necessary what our magi would plan to do. It would be anyway a perfect valid choice.
Since the Maga has realized she cannot reasonably, with her own limited means, reach the sword for targeting, she has settled with this plan, for the time being.
She has an Intangible Tunnel established on the Companion, wich she uses to monitor what the Companion is doing for the next Moon.
She then will use a MuVi effect on a variant of Ward against Demons, which she already has as an original Formulaic Spell she invented for herself, to counter the effect from the sword or the demon.
She can somehow manage a spontaneous MuVi effect for a total change of the Ward against Demons variant she has already mastered.
How about the young maga buying a lab text for Seven League Stride?
Can she invent from text, and does she have a season to invent it?
Then she can just teleport there and grab the sword.
Even if the AC to the grog could somehow be changed to an AC to the sword, bringing the sword back seems quite a hassle - if weâre talking a young maga and spontaneous spells?
The route passing through Seven League Stride is not viable. It could work, but as you just said, bringing the sword back ist just too much of a hassle. On top of that, she just doesn't want to do it plainly (she wants to avoid antagonizing the companion.)
Besides that, the maga just recently discovered a much bigger issue. She had the chance to target the sword with a R:Sight formulaic variant of the Intangible Tunnel, but she has not yet able to affect it entirely, due to its Magic Resistance.
Just another can of worms opening up for her. If she could not penetrate with a formulaic, the chance she will be able to destroy the sword with a spontaneous are slim...
She will retry again in the future, with specific spells (Mastery on Penetration for the Tunnel, and specific high penetration Demon Eternal Oblivion variant tailored for the sword, or she will just melt the sword I guess).
The sword has MR? Forget about spontaneous magic I guess.
This is going to need highly specialised magic.
Interesting situation, Iâd be glad to know how this turns out.
Even if the maga wants to do it discreetly, I still think transporting in close by some way is the way to go. Sneak in at night and switch the sword with an innocent duplicate.
You canât solve everything with a few nice spells. Not young magi anyway.
But the thing with hitting another target that one you have an AC to - thatâs really interesting.
I'll let you know how it will turn out.
But yes, for the time being she cannot do much. There should be another chance soon to land a R:Sight or R:Voice formulaic Tunnel, she has improved her Penetration and raised her Arts.
But then, what will she do after she manages that ?
She now knows that what she thought was a minor issue is something nastier that needs to be addressed (it's a recurring antagonist of the covenant). But with that MR in place, she has no chance to affect it with spontaneous spells, and this means she will plan for a more direct approach.
She wanted to recover the sword in order to investigate it, but now she is more in a "damage control" mode, as soon as she will be able to target it she will try to break it.
I still have to figure out how 
Maybe a R Touch Pe Te spell? Low level, get high Pen?
Can it be destroyed by mundane means?
Maybe use magi to travel to the sword, and to learn more? Not to fix it all by magic, that seems hard
If she doesn't pursue the stealth route, she will go with multiple casting of Blade of the Virulent Flames (or a sustained variant of the same). Her favourite Art is Ignem, she can handle the MR when casting from her Sanctum (so yes, she still will pursue the Intangible Tunnel route).
So using Blade of Virulent Flame in excess to eventually ruin the sword?
Nice! Good idea, good way of using the favoured Form.
Maybe that also freaks the Companion out, and he rejects the sword as dangerous?
I can see how you would like to cast the spell from your sanctum, for maximum Penetration. Itâs a tricky situation. Somehow, now, I want a spell which can actually allow a spell through a Tunnel to affect something else, or to shift the AC.
If fast travel with magic to the sword is not viable what about mundane travel, was there mention of economic challenges? If so, use magic to cheat or steal in order to finance the journey. Itâll take time for the maga, but itâll also take time to take the route of inventing several spells so specialized they may never see use again.