Wait a second, It literally didn't even take but a few panels after being stated he could not take any dmg from anything at all... for him to get slapped and take dmg which he even notes "hurt".
I am seriously confused and get the feeling chapter 2-4 will likely continue to confuse me cause as far as I can guess, He's gonna take several attacks that will do nothing to him and won't hurt him.
Still gonna read but that skill needs a bit more explaining.