There are many suggestions but this one will benefit ALL players.
New stances will make all the heroes out there look more unique and dynamic looking, here's a few ideas.
Zombie: Already available for NPCs
Power Armor: Already available for NPCs
Sneaky: Similar to the stealth ability
Terrifying: the stance used for the Summon Shadows ability
Pumped up: For Martial arts users wanting to keep on their toes.
Brooding: Keeps their head down, for hooded heroes.
I have many more, However I think its best that the available stances are ported to us first.