How about this?

The majority of learning by watching/interacting is covered by prac'ing it up to 75, then you need to learn for yourself. However after 91%, you need to fight against others using your weapon to get that final few percentages. You've mastered the weapon as best you can by watching and hitting things, but you can still learn a few moves by actually battling another master of the weapon. My idea? Make weapon mastery mean a bit more potent at 100% and make it impossible to learn a weapon past 91% without fighting a warrior specialized in that weapon. Your spec weapons you can perfect without interaction as a warrior.

Its kind of like with programming. You first start programming by reading what others do, and then doing what you can til you are competant (75%). Then you work on your own and build things up from scratch yourself, and hone yourself to professional status (91%). However to become an artisan, you have to learn some of the techniques employed by a truly gifted programmers (quake 3 source). Etc.

It'd be cool because then you could put in a quest-spec for someone who got all to 100% by training with various warriors/weapon masters and thus got an all around spec (3-4 skills from assorted weapons).