Holy [censored]! I had the exact same idea a while back. I always thought just "buying" a spell was kinda lame. I think that maybe only mages should sell spells and should give you an optional "training" lesson or to. Perhaps you could be rewarded with extra XP in that spell area for doing the training.
I think it would help the feel of learning spells a lot. I mean the act of learning spells is a very important part of the progression for a magic user. It should feel special, not just like you're buying something. As it is in Oblivion there's barely any difference in how it feels to buy a spell vs buying an item. I do like the idea of giving you some little bonus for actually going through with the training instead of skipping it. Maybe like a quarter to half a skill increase in that magic school - nothing that would be missed or impossible to make up for people that skip the training.
That'd be potentially a whole heck of alot of animations, for something that's really minor. :shrug:
No, the animations would be the exact same animation that the NPC or player regularly uses to cast any spell. The idea is that when you purchase a spell, the NPC demonstrates the spell, then instructs you to try it. The only additional animations required would be a possible "spell failure" animation, if that was included (as in the first couple times you try out the spell in front of the trainer it fails). But that wouldn't really be necessary, just a little extra to make it feel like you are learning the spell and don't immediately use it perfectly.
When I say each session would be different, that's just a result of the types of spells. For destruction, the trainer would conjure an enemy or take you to an immobile target, and cast the spell on that. For spells like charm, the trainer might just cast the charm on another nearby NPC and tell you to do the same. There would be differences, but not necessarily new animations that aren't already in the game anyway. Mainly I was responding to the sentiment that every time you learn a spell there would be some little cutscene or non-unique animation that never changes regardless of the spell, which wasn't what I was suggesting.
But if we're going to have animations for wood chopping, mining, cooking, fishing, smithing, alchemy, and enchanting, I don't see why this idea seems so farfetched.