I'm surprised the guy lasted long. I guess this shows how ineffective stabbing blades to the head are. The skull is probably smooth so whenever they tried to stab his head, the blade would either be redirected elsewhere or it would only make small cracks in the skull. It would definitely bring terrible pain to the victim. A blunt object, such as a hammer, would've been more effective in causing the skull to break and the brain to get crushed.

In zombie movies and shows, I always wonder how in the world their knives can just stab a zombie's skull without the blade either simply being ineffective or outright breaking.