I actually already suggested making a list of attuneable stances. I think it will be really cool to have stances that are learned just like spells and equipped like them. Perhaps the number you and I can attune to can scale with Intelligence? That will give melee characters a reason to not be an idiot (I like having an Intelligence score higher than 7 for roleplaying >.>) other than being a caster/warrior hybrid. I also think some of these can reflect regional differences. For example, Astora (which I think mirrors England and/or France) used more defensive techniques, while Germany (perhaps Thorlund?) was famous for it's VERY offensive style. A lot of fencing came from Italy and Spain. (perhaps Carim?) I think that has a lot of lore potential, too.
TinyPantha's partially right. Rapiers weren't handled in the same manner as smallswords; neither were they handled as arming swords, though. Techniques, stances and weapon designs for civilian dueling weapons (fencing with epees and smallswords) were quite different from actual military and mercenary thrusting swords. The actual manner of employment wasn't the slash-and-thrust methods used by arming swords, though; that's counterproductive to the very point of using a thrusting sword and will actually quickly destroy a thrusting sword.
The Souls series has thus far been 1300-1500's in terms of both technology and culture, not 1600-1800's. That being said, I think a fantasy game set in the 1600's sounds awesome.