While Thor was studying Aslan, the Lion was studying his opponent. The missing eye is obvious. But there are other obvious things too. Like how heavy the other man, and how he would go down hard if struck just right. And that armor might be worn for protection, but it too will impede movement.

Aslan is a Lion. And this means he has all the blessings of the Giant Cat. And so he is very quick on his fight. Dodging out of the way, he Thor attempts his first strike. And moving quickly to the Thor's side, to avoid that second hand-strike.

Aslan uses his weight to slam up against Thor from that blind spot, trying to get him off balance for a second. And aims two quick clawless strikes of his paws at the other man.