wait he still doesn't realize he's a demigod? He has a spear that will kill anything
His body is abnormally resilient, but not strong. Well, he must be above average, but not beyond human standards.
It's only the tool that allows him to do just about anything effortlessly.
He considers the tool as distinct from himself, but others consider it as part of him. This can make sense since there is likely no force in that world that can keep the tool away from him save for the gods themselves. So it's this difference in perspective that leads to this hilarious pic of puzzled Kuros.