If hunchback is perhaps unacceptable, how about humpback? (And our descriptions could give a reference to this thread.) To refer to them as Richard III or Notre Dame or ... hilts would be a bit misleading.
Yes, humpback or Quasimodo (reference to Notre Dame) would be suitable, or perhaps "one-armed as you will notice that the left arm is vaguely visible but the right one is cut at the shoulder level.