Shikkaku Mon No Saikyou Kenja~ Sekai Saikyou No Kenja Ga Sarani Tsuyoku Naru Tameni Tenseishimashita~ (bestlightnovel-com)

In a certain world, there was someone who excelled in magic combat, people called him 『Sage』. Seeking the strongest combat art, he devoted himself to research every magic and combat arts in existence. And the conclusion he arrived at was very cruel, 『My body is not fit for magic combat』. Yet he didn’t give up. He seal…