I was wondering the same thing. I don’t recall seeing any injuries done to undead. I suppose injuries to them would not make much sense, since most injuries affect the soft tissues and innards that they don’t even possess. If you can carry a shield and swing a weapon without any muscles or sinews or organs or circulatory system, I suppose the mere cracking of a segment of bone should also not affect performance, since the performance doesn’t depend on the usual laws of physiology.
