I think his pteranodon wings are normal, tough as rest of his body or perhaps tougher a bit.
I was thinking about his base form wings, they are the ones that Zoro wondered about if they are used to fly...
Maybe they absorb damage and feathers fall out as he takes damage?
This reminds me of Danzo's eyes closing as he keeps dying... Two mysteries - wings and fire.
King has by far the most mysterious abilities so far. Looking forward to see what they actually are.
In Two Piece, Zoro's attack isnt one of only two who harmed Kaido the most in the whole world, ever?