Yeah, he's really strong. Steel, in case you didn't know, is really heavy and really strong. I'll admit, steel does rust, meaning it does disintegrate over time, but if you were to make a hand-to-hand attack to him, especially at a hole in his suit, that would hurt a lot. Not only because of how strong steel is, but also because you now have tetanus, which is extremely painful and a huge medical problem. On top of that, William Afton's corpse is even a danger to be around in the first place. A small list includes hepatitis B and C, HIV, cholera, and tuberculosis. On top of it all, his suit's green tint is more than likely caused by mold, which is also extremely dangerous to be around. Another small list includes brain fog (not too dangerous on its own but could impair your ability to fight him), irritation of eyes, skin, nose, throat, and lungs. and still, steel is extremely dangerous if a large amount of it (like a steel hand being propelled by more steel) would cause possible concussions if he throws his hands at you fast enough. Add on top of that his unnatural bloodlust and serial killer intelligence, which is still near perfectly in tact due to him speaking in FNaF 6 and UCN. His word choice also shows a heightened intelligence and ability to comprehend when he is being tricked because he says "What a deceptive calling. I knew it was a lie the moment I heard it, obviously, but it is intriguing nonetheless." This clearly shows intelligence and he's just straight up a fucking serial killer with an (estimated) 5 year long reign without getting caught by police.