Sometimes in my game, I can get a critical attack that does more damage than a normal one, its somewhat random though.
I can shoot them in the face one time and get normal damage then do it again and get a critical attack. You know it's a critical when it does that hollow knock sound when it hits them, but I've only found it works with a bow, haven't properly done it with swords yet.
And in case someone thinks I'm mistaking this for a sneak attack, this is while we can both see each other and attacking.
However, it's not just the face that has given me critical damage, I've shot them in the chest too and it's happened.