What does "chance to dismember" mean?
Solution 1:
My understanding is that when you are fighting an enemy, particular human ones, there's a chance that one of your fast/strong attacks will activate a killing animation, which instantly kills the enemy, even if they are at high health, which makes it particularly useful.
So dismembering is essentially an insta-kill, but I think I mostly see it occur on humans, not as much on monsters, if at all.