Ironically, the return-to-pose draw back motion is my favorite part of this animation. Why? It's the only piece that has any SNAP, any deliberate motion, and anything hinting at some serious impact.
In fact, your signature, avatar, and this piece all three are rather slow and force-less in my humblest of opinions! Don't get me wrong, I love the sweepingness of your signiature in particular, but all your animations seem to lack the aggressiveness and lightning-motion that attacks should have.
As reference, track down a post from Gil and check out his avatar. It's got a sense of smashy smash to it.
Alternately, and for a far better resource and a read, check out this if you haven't already:
http://www.wayofthepixel.net/pixelation/index.php?topic=3421.0Specifically, I'd suggest looking for the floating fire mage chick and how much fuggin' impact there is on that animation.
Love the motions, though, and how well he holds his form. If you work on the timing and force of this, I'm sure you could make it EVEN MORE impressive!
P.S. I'd love you if you had it in you to remove his helmet and make that orc ROAR!