Manga Shikkaku Mon No Saikyou Kenja

In a certain world there was someone who succeeded in magical battle, people called him "Sage." In search of the strongest martial art, he devoted himself to the study of all existing magical and martial arts. And the conclusion he came to was very cruel: "My body is not suitable for magical combat." And yet he did not give up. He sealed his soul with magical art and was revived in the distant future. And the theory of magic in a completely changed world that he saw was incredibly low.