In wuxia fiction, many of the most powerful hand-to-hand combat techniques use the flat palm of the combatant's hand as the striking surface. Why use the palm of the hand, however, when the fist does more obvious damage? I'm not trained in the martial arts, so from my layman's perspective, I think I would do more damage if I hit someone with my closed fist than I would with the flat palm of my hand. That being the case, why is wuxia hand-to-hand combat dominated by palm techniques?