I'm newly running an Ars Magica 5th edition game, and I'm finding the Confidence mechanic feels a little out of place so far.
As far as I can find, it is only mentioned in any detail on Page 19-20. If played straight it allows players to give a little boost to a roll about two or three times a session, and the ways it gets rewarded make it pretty clear it's a way to give a small reward for good play. I'm not opposed to using such carrots on my players, but the one game of Ars I've played didn't use them (I'm only now spotting them as I reread the rulebook) and I never noticed their lack. Admittedly, it was a fairly short-lived campaign.
This looks at first like a variation on Fate points from Fate or like Inspiration in D&D 5th edition. In Fate, those points are woven into the rest of the system and are part of the assumptions used by other parts of the system. Removing them makes other parts of the game not work as smoothly, sometimes in non-obvious ways. (For example, without Fate points there's less reason to accept concessions.) In D&D, those points are only mentioned in one or two places and I've seen them be excised from the game entirely without problems. Inspiration is vestigial enough that I have seen it forgotten by entire tables more often than I have seen it deliberately houseruled away.
Could someone with more experience in Ars Magica advise me on which example Confidence more closely resembles? If it only is tacked on by a couple of pages, not referenced by any other mechanics, and other numbers are not balanced around the assumption that the PCs have access to Confidence, then I'm going to remove it. If it is referenced by other mechanics (my first thought was it might be used to resist compulsions, but Rego Mentum spells seem to go against either the usual magical defenses or against Intelligence) or if the other numbers are balanced with the assumption that Confidence exists then I'm going to keep it.