Well, I was figuring his deadlift caps out on anything at least 10 meters bigger than him- larger stuff can still be lifted, but he can only barely move while holding it up.

As for the martial art and grappling, I was going for an angle where he was interacting with the ancestors of the ancient Greeks and learned their fighting style to defend himself against other monsters, and might have taught them something or other in exchange, leading to the depiction of titans as givers of knowledge and secrets in Greek myth.