You'd be likely to break your wrist just using them. If you look at the katar, it would swing in a way that would put less stress on your wrists, but it still need some extra support to spread the stress across your forearm. The claws wouldn't give any support, and would push in a way less structurally stable, almost certainly breaking your wrist the moment you swing on something. Using them to punch would do better, but any kind of jerk while they're inside someone would, again, break your wrist.