He has courage which is his greatest strength. As long as he believes in himself, he can do anything, but that courage sort of led to his weakness. He became prideful. Though because of that, he started thinking ahead of time. He freed most of his friends and himself from the cyclops and got them to the ship, but still he lost 6 of his friends in the whole scenario.
(This was my answer in my school)-Shy
Hoped I helped!