Those two injuries are nothing vs Sion's countless deaths. The guy literally pulls himself back together with the force after being 'killed' in battle countless times for 40+ years. He literally pulls a Lasarus right after being killed again and again... he doesn't require greater skill to win in a duel, he can actually just Lasarus style rope-a-dope them till they tire and there is an opening to stab them with. The guy flat out is a Sith Zombie meets Berserker meets tracker, so he's a hunter not a skeemer... his only cares about killing Jedi and his master (Darth Revan's former master btw). Here is the quote on his injuries from wookieepedia He literally is the opposite of Plagueis in many respects, he could only save himself from death since but not others, his power was purely instictual and not gained through wisdom of any sort. Ironic that after all that he died by pulling a Padme... just losing the will to live.