In reading HMRE about the Gruagachan, one spell caught my eye. That is the set of spells to grant / increase / decrease an ability. I would have expected those to also be existing Hermetic capabilities. But looking at Creo Mentem and Muto Mentem (which would seem the relevant combinations) I find no mention of them. Are these capabilities that can be produced by hermetic magic, or does it require a breakthrough of some sort (with all the challenges HMRE mentions for getting insight into Gruagachan magic)?
That would be impossible for Hermetic magic, as Mentem can create memories or thoughts, and while those could give some insight (lower case) into how to do a job, they wouldn't give you the muscle memory or know-how to actually do so. Gruagachan magic on the other hand can actually grant Blessings, which could in fact increase someone's skill in something, as they do not the mind, but rather the entire person.