Nicely done! Two issues though: its size is really too big at the moment (test it at any model and you'll see). You should at least halve it. And it needs a death animation, as said here, it should only disappear. (else it will remain visible when unequipped)
Doing a mirrored version could be useful to attach to units which aren't left-handed. (Or some animation of it turned around for 180°)