What can be an Arcane Connection to what?

As the subject says, and this is a question that came up in my group. First, some things can be arcane connections obviously, others less so. I was hoping for help figuring some things out. First, is there a place (other than the main book, ArM p 84, where it describes what can be Arcane Connections? As far as PEOPLE, it's pretty obvious, but less so for objects. If you want an arcane connection to a relic sword, is the sword's scabbard a connection? (I would assume it is). How about the pedestal where it is kept constantly? What about the pedestal it's kept on at night, though it's worn during the day. What about the room it is housed in? Gah, so much possibilities.
I can assume Arcane Connections are not two-directional. A splash of blood is a connection to a certain maga, but I assume that Maga isn't a connection to every splatter of blood she's lost. Otherwise that leaves all sorts of strange side-effects.
The other question, can one thing be an arcane connection to multiple things? If two artisans craft an exquisite sword, is that sword a connection to both of them? If a group of magi work together to enchant an invested item for their covenant, is that item a connection to all of them?

This my personal take, and I don't know if it is supported in canon.

An Arcane connection is dependent upon the Laws of Contagion and Sympathy. An arcane connection requires that there have been an unambiguous connection with the Target. The sword's scabbard is a strong connection, and probably unambiguous (unless multiple swords use the scabbard). If the Pedestal is only used with the sword, then after a while it should develop a sufficient association with the sword (but before the sword, the pedestal was first connected to the block of stone it was carved from, so that connection needs to fade). The room has a part-time connection to the sword, but it is diluted with by the room's connection with everything else stored in it, so hardly unambiguous.

I am sure somebody can explain it in terms of the laws of sympathy and contagion, but I think of it in terms of mathematics - basically a subset is part of a superset, but a superset is not part of a subset. In other words, an item is the sum of its parts, so a part (eg a splash of blood) belongs to the greater item (eg a person), but not the other way around (eg a boulder is not a connection to a chip off the block).

This should not apply in the case when an Arcane Connection is Fixed in the Lab. Now an entanglement has been created and each should be an arcane connection to the other (including a Familiar and Magus, or a Talisman and Magus)
There should be InVi guidelines to detect such fixed arcane connections.

Both have put something into the sword, so the sword is metaphysically contains part of both artisans. However it is not a strict subset of either artisan. So there might be a very weak arcane connection, but almost certainly less than the connection to either the original ore or forge. Unless you have someway to distinguish between Arcane connections, I imagine by default you connect to the strongest arcane connection. Sort of like one has a better Penetration bonus. As far as I know Hermetic Magic doesn't know how to distinguish potential arcane connections / select weaker ones.
But even if the arcane connection to one of the artisans is the strongest, remember that such an Arcane connection eventually decays, as the sword becomes associated with its new owner.

In many ways, standard Hermetic Magic only has a very simple, limited ability to deal with Arcane connections.

Ah, arcane connections, these little nightmares!

The corebook says that mystically arcane connections are a still part of the target, so drops of blood are arcane connections to a body (they were parts of it, and still mystically linked to it), but the body isn't an arcane connection to every one of its blood drops. If it were magi would be pretty good at getting rid of arcane connections to them with one In and one Pe spells, and Wizard Wars would be so terrible hard and boring. Sympathetic connections aren't that simple and are quite hard to came clear with.

I also think I read somewhere that something could be an Arcane Connection to one thing, which helps solving some issues but creates a whole new set of problems, with Magi being an obvious counterexample, connected to both their familiar and their talisman.

So my take is to let things loose and when they don't cause trouble let them go, and when they do shrug and assume that as Ivgreen said Hermetic Magic is quite limited and simple when dealing with them, and that some things thus can't be done.

So about the scabbard I'd say yes, but a gem removed from the handling of the sword would be a even better one, having been an actual part of the sword (also a valid one would be a wound caused by the sword if you fix it fast enough: In our games a dragon wounded a magi and he fixed the wound as an arcane connection to the dragon, which was quite cool and was fatal for the dragon). The pedestal gives more trouble as there is more logic for it being an arcane connection to the room it stands in (being part of it) than to the sword, so I'd push against that. The sword made by two artisans would cause some issues but one of them would have had a more prominent role (having designed it, or having poured the steel, or whatever), and the sword would be a connection to him alone. And if a group of magi work in an enchanted item, only one can have the lead with the others acting as assistants, and so the item would be an arcane connection only to that magi. Unless you want to start rewriting any R:Arc. spell adding them a couple magnitudes to have T:Group or start to have these spells failing all the time.

If arcane connections aren't two way... explain "Humans are Easily Misplaced" RoP:M pg71

Faerie magic's range of Bloodline traverses Sympathy the opposite direction. That is if an object is a connection to the maker, then a child would be a connection to the parent. Bloodline works the other direction, parent to child. Sympathy is bilateral, in the game and concept.

I'd say the scabbard would be the same as the gem, depending on if they were made for each other and are halves of a whole. Room and pedestal depending on the veneration, but yes.

If they do, explain every other R:Arcane spells.

Though that's not a spell, but a power, and one can go more cheerfully around powers (after all if they aren't hermetic stuff they can get rid of some hermetic constraints). As I spell I wouldn't allow it; the caster wouldn't have any arcane connection to the intended target (though the intended target would actually have the arcane connection of the magus who oddly rubbed against his legs). As a power it is fun if only because it suggest hidden reasons for cats rubbing against people.

So other powers designed such would be good.

The connection is bilateral. If using a walnut in a potion helps magic on brains because it looks like a brain, using a brain has an effect on a walnut in the same way.

One could explain the cat and scent by saying the scent is part of the cat still like a talisman and it apples to cats only.

In the OP a scabbard has a connection to the sword and the sword has a connection to the scabbard.

I would like to invoke other fantasy stories where in magic can affect a victim of a wound by virtue the caster has the weapon or claw which caused it. While there are instances where the blade itself is the origin and the Magic acts like poison, it's not what I mean.

Personal range spells affect a talisman and talisman affects Magus. The description for talismans states "you always have an arcane connection to your talisman, making it easy to find if lost (but a hazard if it falls into enemy hands)", this is one of the reasons I consider it bilateral. Elsewhere it's mentioned an item is a connection to creator, in a general sense. It could be particular to talismans, though I'm inclined to think otherwise.

There are a few possible reasons for this to work; Really, I think it's easier to view it as 'this power doesn't work quite right' instead of 'this power proves that arcane connections are two-way', especially when there's no other things supporting this. The other possibility is that a cat scent-marking something creates that arcane connection for a short period of time. Really, the power CAN work fine if you just remove the specified statement that cats can create arcane connections by cuddling. Perhaps the cat is making himself an arcane connection to that creature?

I kind of prefer the idea that a sword made by two artisans is an arcane connection to BOTH artisans, but not to one or the other... but I could probably also accept that it is a connection to either.

Another possibility is that Arcane Connections are two way, but are bound by awareness. Magus Hemophilia is an arcane connection to all of the blood he's spilled. He can cast a spell with R: AC to destroy the blood he's left on a sword if he's aware of it. Since the main book (p84) uses the term 'as long as she is currently aware of the Arcane Connection'. I think I still prefer the interpretation that it's not two-way though. Thoughts?

Technically, "Humans are Easily Misplaced" RoP:M pg71"is a power, not a hermetic spell.
Some of these are a bit borderline in design, and there is technically no requirement that the powers of magical creatures follow the same rules as Hermetic Spells.

That's a pretty big cop out. If that is the case why does the description go the length to explain the arcane connection? Instead of saying 'this is different than hermetics' which is EVERY where else.

Talismans.

If he casts a spell to destroy his blood without proper targeting, he dies. He is an arcane connection to all of his blood. Using Intellego to find it is a bit different... the power could be accidentally not including an increase in magnitude for "Part". There are a few powers that seem mildly off in RoP:M.

Using Intellego to sense your blood, use imaginem to see where it is, open a tunnel but use part?

It can also be it's for cats and other animals that sense smells way better. The power does imply the cat has an arcane connection to the person, which would make sense with the Law of Contagion. So the cat isn't an arcane connection to the scent he rubbed on the human, he has an arcane connection to the person because he rubbed on him. I would guess it wouldn't last long at all, which probably is why my cat does it ever 10 minutes.

I'm leaning towards Talismans/Familiars being an exception, because magic makes them PART of the magus and vice versa. You're not wrong though.

If we go the two-way route I would probably say that casting it without being AWARE of the spell causes it to do nothing - just like shooting a BOAF at an i

And this is something I actually agree with as an idea: The cat creates an arcane connection to the target by scent marking, and I'd probably put that duration at 'hours' as the default, but that's up to interpretation.

No, it doesn't have to be. And walnuts are fortunately not arcane connection to any brain (unless you put one inside a brain for some time, maybe?).

Items tend to become AC to those who use them thoroughly, so swords tend to become ACs to their owners, not to their scabbard. Unless you want items being ACs to lots of things, which is quite problematic (before pointing me that that already happens with magi, talismans and familiars, I know, and that's exactly why I'm saying its problematic, and should be avoided whenever it's possible. Unless you want to allow a walnut to be an AC to every brain, of course).

In fact it works the other way around: on the Image of the Beast spell it says that wounds caused by animals are short timed ACs to the animal which caused them. So weapon wounds are ACs to the weapon who caused them, but weapons aren't ACs to the wounds they make. But that doesn't stop magic from affecting the victim of a wound, may the caster have the weapon: usually after the wound there will be blood on that weapon (unless you are using concision weapons and having a nasty SG; its always safer to work with slashing and piercing weapons, just in case), which is the actual AC to the wounded, being blood part of him.

That description also says something about the Talisman becoming mystically part of the Magus, and that's why it serves as an AC to its creator, I think. And the creator have an AC to his Talisman because, well, it's his Talisman, and that's one of the benefits of bothering making one, like giving you bonus to certain spellcasting rolls. Unless you want to argue that any ACs grant these bonus, of course.