If you attack and miss you still learn regardless of how much skill you have vs the critter you're attacking.

With 395 small edge and 331 melee mastery if I stance attack to 0 and just repeatedly feint at a sleazy lout I was able to get both skills to 10/34 in less than 60 seconds. I could have continued all the way to mind lock but figured this was conclusive enough. If I actually land a hit I get 0 exp.

Also, stealth learning doesn't seem to hard cap. 500 stealth got to up to about 8/34 on louts mostly just from just retreating/advancing while hidden. Slip-stalk and backstab also added stealth exp so it builds even faster if I use those. I noticed this originally while collecting bones from lesser sluagh since I ended up mind locked in stealth. It works faster on tougher critters but I still don't think we're supposed to be learning off something that has no hope of spotting us.

~Minstrel Ascot, Bladesinger of M'riss