Actually i got a better suggestion, give them a hand mesh that looks like a spider's leg, and make it moderate in length(big one like u see in the giant-spider-kill-human movies). Since the hand is in a static form, no vertex animation is required. Then give them an invisible mesh for the one handed weapon and only allow swinging attacks. Thus, u have a perfect spider like weapons without much trouble. The only trouble you would most likely encounter is to position of the mesh in wings3d so that it would look proper working as a arm mesh.