Currently you can only activate an ability after the previous has done all its motions. This is really annoying as it really doesnt allow for a nice chaining of abilities. Same for health potions, which you cant use unless you stand still.

So when i almost dead, i cant pop a potion cos ability animation hasnt finished yet. Pretty annoying.

Or i cant pop my shield and a shout all at once when i need to, cos i am waiting for an animation to finish still.