This Is the Wizard’s Secret Weapon

On a bloody battlefield, the master swordsman Rix finally gives in to his deep-seated dislike for warfare. So he fakes his own death to go into retirement! He starts fresh by entering a magic school...despite his magical aptitude being zero. However, alongside the scholarship student Shino, he's ready to work hard. Even her cold attitude doesn't discourage him! Using his swordsmanship prowess, he overpowers his magic-wielding peers-inadvertently smashing through anything that's common practice at magic school. In the process, his skills catch the eye of the Imperial princess. She tries to recruit him into the army, but he shoots her down. He doesn't want to be the strongest— all he wants is to live a peaceful and enjoyable life!

(Source: Yen Press)