Not sure if anyone has suggested this before, but I've always been frustrated with the options for wolvering / shredder type claws.http://www.minifigcat.com/shop/home.php?cat=374
Some use the bullet bunch from brickarms.
Some use the new one from lego
This may be tricky to do since the parts are so skinny, but my idea for these claws is to have a vambrace with additional spikes protruding forward over the hand.
This would allow the use of the hand for other things and give the appearance of spikes projecting from the back of the hand...