It is possible that this is answered somewhere in Canon, but I currently don't have access to my books.
Parma Magica is technically an Arcane Ability if I recall correctly, even though it isn't used much like other Arcane Abilities.
So mechanically speaking, the Affinity with [Ability], Puissant [Ability], and Learn from Mistakes [Ability] virtues should work for it, no?
Well, maybe not Learn from Mistakes Parma Magica, as I am not aware of any time you would make a dice roll with Parma Magica
So what are people's opinions with virtues like Affinity with Parma Magica and Puissant Parma Magica in their Sagas?
A magus is definitely using (hence practicing) with PM every day (twice a day usually), so I can see Affinity with Parma Magica could work.
But Puissant Parma Magica? Perhaps not for a just-Gauntleted Magus, but maybe as a good Twilight effect?
Or just any magi who happen to have a natural knack with it. Think that it could be something to be frequently expected in combat magi (hoplites and so), so it just mean that any character that gets it will find that path easier, as another character with Puissant Magic Theory will probably find his natural path heading to being a successful lab rat.
In every saga I've played face-to-face this hasn't been controversial, there's usually at least one player who wants to take Puissant Parma Magica. We allow just the same as Puissant Finesse and Puissant Penetration. Of the three, I think Puissant Finesse was the most popular.
Technically no - on HoH: Societates p131 under the third application of craft magic it says "This application of Craft Magic also allows a character with a Supernatural Ability or Virtue that only affects himself to craft items that other characters can use for the same effect, though only if the activity requires the crafted item to perform." The examples given are Puissant Single Weapon in a shield (fair enough - you use single weapon skill with a shield) and Enchanting Music in a drum (fair enough - enchanting music requires you to play music, so an instrument counts).
What item is required to do Parma Magica? What item could possibly enhance Parma Magica? Unless your saga has house-ruled in items to enhance Parma, you can't use Craft Magic to perform Parma Magica.
checks lesser craft magic in Rival Magic Oh hey, the minor supernatural virtue Lesser Craft Magic is worded slightly differently, and says "He can instill any effect of a Supernatural Ability he himself possesses;" but this doesn't help - Parma Magica is an Arcane ability, not a Supernatural ability.
Of course apprentices learn it at the end of their apprenticeships when they have significant Art scores. So it can't be a regular Supernatural ability or no parens would ever get their teaching SQ high enough to teach it.
I am now wondering how easy it is to learn Parma Magica.
After all, one of the things you can do with PM is extend protection to other people. One might suppose there are Magi who regularly extend their PM to cover their apprentice - eg a mage with Blatant Magic might want to remove the Gift penalty distraction so that they can teach their apprentice.
If the apprentice, who has to be present during the PM ritual, regularly sees the PM ritual performed, might they not learn it?
At the very least, I now realise this could be in-game justification for either Puissant or Affinity with PM.
Unless the parens always has the apprentice looking elsewhere/blindfolded during the PM ritual...
This is actually required by the code. Not extending your parma (when teaching) is considered abuse (turning your apprentice into a mule so they pay attention is not for example. An interesting question is does Jerbiton have to do this as well even though most have Gentle Gift?
Serf's Parma - I believe that there is a "trick" that lets the Parma go off, and that it is this last trick Apprentices are not allowed to see. I think it is only the last step of the Parma that is the Trick.
I would assume that at base, it's rather difficult to learn, for 'plot' reasons - it's arguably the core reason for the magical supremacy of the Order of Hermes, and if you make it comparatively easy to learn, you risk radically altering the balance of magical power in Mythic Europe - knowledge leaking outside of the order is quickly going to get into Join-or-Die territory, and if it's happening at any sort of scale, that's one of the few 'war-level' scenarios for the OoH imo.
I would say that most magi would extend the Parma simply to give their apprentices low-level across the board magic resistance - this protects them from various forceless casting / magical effects they might encounter generally. To me, the 'social effects' of the Gift aren't the primary driver of the Parma extension, it's that ostensibly you're supposed to protect your apprentice from other Wizards - even if you're not good enough at Parma to protect them from anything but forceless casting. Apprentices are also classic targets in Wizard's War, and many of the earliest customs of the OoH are legacies of a much less cooperative time between magi.
I don't have Apprentices any more (lost in a move), but I am pretty sure the social aspect is why Parma is required during the teaching season.
In the non-teaching seasons, apprentices would need/want the parma for lab assistant work, so they pay attention instead of trying to hide or murder the magi (overstated for effect there), but otherwise they are on their own. If the Magi is just reading his books to learn a spell, or off adventuring he might just leave his Appentice at home. And just like normal, Parma fades and sunrise and sunset, and it might even fade at distance (but I am less certain about that!).
Even an 'evil' magi, who abuses his apprentices (and there are many many story hooks about this throughout Ars Magic publications) is required to use the Parma for teaching seasons or else they are considered to not be teaching their apprentices correctly and can have them removed from custody (depending on tribunal and politics of course).
I've always been under the idea that there was more to magic than just Words and Gestures. Just like an apprentice watching their Master yell "Creo Ignem!" and finger-wiggle won't let a new apprentice cast a masterful Ball of Abysmal Flame, watching their master mutter "Parma Parma Parma" won't let an apprentice (or other Gifted outsider) learn how to Parma Magica properly. I got the feeling that there's a particular internal spiritual-mental alignment necessary, or vibrating your Gift in a particular frequency, or something....
Basically, there's more than perfect mimicry of gestures and incantations needed for doing magic, Parma included.
It definitely fades at a distance. According to p. 66 of the core rules, "it lasts as long as at least one character can see the other" (talking about the person extending the Parma and the person to whom Parma is extended). So once master and apprentice are out of sight of each other, the Parma protection ends.
I've always thought that would be annoying when your apprentice is helping you in the lab. Every time you have your apprentice fetch something from another room you have to re-up the Parma protection. One of you needs to use the facilities? Parma needs to be re-upped. Third party Parma protection is really very fragile that way.