Melee weapons in general are fairly limited. It would be a bit more creative if you could add different animations to the swing other then the simple arm swing provided with the block dude. But, adding more animations to the block dude can really only be done by Badspot, and other ways to bypass that are kind of complicated.
It's possible to simply include the hand in the model, and then just add in all the animations with that model, but then you'd need to find out a way to recolor the hand like the actual block dude's hand to make a better replacement. On top of that you'd need to figure out a way to "hide" that extra hand in 1st person view otherwise your hand won't be exactly like the block dude's hand now will it?
The easiest melee weapons are the heavier ones that don't require any real action at all, like the chainsaw. Sure those can be neat but it would still be pretty awesome to add a little diversity to direct melee weapons.