Yes, that's right.
I've almost finished fixing mistakes I'd made before, one of them about the difference between the V&F versions of Cyclic Magic and one about exposure during seasons of vis wages. Meanwhile I've had to travel across the country and back, so I'm catching up on some things. I should be able to post post-gauntlet seasons very soon.
I read the attunement rules differently: Every season you spend in your lab either opening or enchanting a talisman, you get an attunement on top. That is how I know it from the games I've played. And I believe there is a virtue in TMRE that clarifies what the poorly written Talisman rules were supposed to mean, which supports my reading of them.
But when first Opened/invested it’s still not considered a Talisman, right? So a Season of Attunement turns it into the Talisman, gaining 1 Attunement, and then any Season of work enchanting or filling with more pawns also allows 1 new Attunement, if possible? I concur that the Core section on Talismans could be clearer.
Yes, You may attune an item as your talisman as a seasonal activity and you must have opened it for enchantment yourself (also a seasonal activity). So it takes two seasons minimum.
A season more, a season less
shrugs
Once it's your Talisman, each season you work on it, even if you don't finish what you're enchanting into it or if you're just opening it further, you get an attunement. The critical part is that it must be your Talisman. So when does it become your Talisman? You must have already opened it for enchantment, which generally takes a season. ("Generally" because Philosophic Alchemy can allow you to open an item differently, though at least a season must still pass.) After that it's still not your Talisman. You must then spend a season attuning (unfortunate double use of "attune" for the same thing) it as your Talisman. Only at the end of that season is it your Talisman, meaning you have not yet spent a season working on your Talisman. But now it is your Talisman and all seasons beyond this will give you attunement bonuses. I don't see that it would break anything to have a house rule allowing the season of attuning as a Talisman to also provide an attunement bonus, though.
Unfortunately, the item must already be attuned before you receive the attack nemeny bonus. And attunement doesn't take place until the end of the season.
Aren't we flogging a dead horse?
This is how it is now:
One season to open
One season to attune-->first attunement bonus
One season to invest a first enchantment-->second bonus
etc.
Is it something else you want?
This is actually a contentious point as I understand it. The season making it your talisman doesn't require Vis so you are not preparing it for enchantment or instilling it with an effect so it doesn't open up a bonus by RAW.
Okay then. I don't make the talsiman primarily for attunement bonuses anyway. They are agimmick and I'll spend enough time on it to open anything I need anyway.
One more spell I'm working on: give a weapon/armor "ghost-touch" (using the D&D term), meaning the weapon/armor can interact normally with ghostly/spiritual things. I have only found one such effect so far to use as a reference point, that being GHOSTLY FORM/PHYSICAL FORM (RoP:M p.94). That's pretty much the right effect, but it's Corpus instead of Terram. I'm confused by the Rego rather than Muto. Maybe due to ReMe "control a disembodied spirit"? So maybe I should be looking at ReTe (plus casting requisites) or maybe MuTe (again, plus casting requisites). If MuTe, I believe base 4 "Change dirt so that it is highly unnatural" would be appropriate along with +2 metal. That's a bit higher base than in the example spell, so not unreasonable. If it's ReTe, probably base 3 "Control or move dirt in a very unnatural fashion," again with +2 metal. Meanwhile, since this would be about interacting with spirits, not about actually becoming insubstantial, there will be a required Mentem requisite, just as with the example effect.
Thoughts?
It’s kind of the reserve of the Tremere spells which give ghosts arms which can affect the physical world. MuTe/Me in reverse, so perhaps use that as a basis? It’s a high basis from memory (like level 25).
What I’m not sure of is how many “body levels” a ghost has. Don’t they just have a might score ? Can two ghosts actually fight and inflict damage?
I thought it would be like two shadows overlapping rather than clashing.
I’ve not read RoPM in ages so probably very wrong.
Is such a spell useful at all. I mean, if the level is too high and it has to penetrate, it'll be quite useless.
You could, on the other hand, create a range touch PeVi effect to slay magic beings in general or PeMe for ghosts specifically.
Ya, they don't have fatigue levels or wound thresholds. So you really just want Deamons Eternal Oblivion at personal range and with a duration and text saying it affects your weapons maybe a Terran requisite. You can kind of shoehorn it that way. I'm being fairly liberal with the spell design rules at that point.
Thanks. I found those after reading your post. Translating to MuTe that would be Base 10, +2 metal. That's unfortunately high. 
But it's doable.
Oh, she could penetrate. Assuming it ends up at level 30, she would probably average about 30 penetration with it. She could manage this much more consistently than she could manage penetrating with Sapping the Gryphon's Strength or similar.
Really? They didn't work on ghosts and the like much in the core book (one example before they produced rules for spirits), more so afterward. HoH:TL disagrees with you. For example, the Legionary ghost (p.126) is "Immune to physical weapons" and has "Wound Penalties: –1 (1-5), –3 (6-10), –5 (11-15), Incapacitated (16-20)," and the Wili (p.127) are "immune to physical weapons" but have "Wound Penalties: –1 (1-7), –3 (8-11), –5 (12-14), Incapacitated (16-19)." HoH:S (p.99) specifies "The physical characteristics of the spirit are only used when dealing with other incorporeal creatures," and that point is why I want to make weapons interact with spirits, acting as if both incorporeal and corporeal, because then there can be physical interaction.
No, I really don't want that. First, penetration would be worse. Second, that would destroy the vis. I want to be able to defeat the spirit and collect its vis.
Note that I've cited books we're using, but this is consistent with RoP:M, which says
As you can see here, spirits may be slain in immaterial form without using spells that destroy the spirit's Might. You'll also note that destroying the Might destroys the vis, which is what was "house-ruled" but isn't actually a house rule; it's the standard RAW.
RoP:M doesn't have wound levels for magic spirits at all. I suppose it just depends on how Ghost builds his ghosts.
Valentine has a really high ReMe. So dealing with ghosts should be trivial for him.
Except that that's not true. RoP:M does not explicitly list wound levels (along with a bunch of other things like Size) for many of the spirits, but it does list wound levels for some spirits - at least one, I'd have to check all the pages on those.
The text specifically mentions that they don't have size because they don't have a body to have a size.