Why is Link’s arm messed up?

Corruption seems to be a big theme in Tears of the Kingdom. To wit, Zelda tells Link that she doesn’t think he is going to be able to stop “him” this time around. That’s probably because Link is, shall we say, a little hindered now. It’s not just the arm, though. Tell me why the official Nintendo Twitter account shared a picture of the Master Sword looking mega busted? I’m feeling some Princess Mononoke vibes, here. Or maybe the corrupted Master Sword is just how they’re bringing weapon degradation back.