Lord Magear no Deshi

When he was very little, the boy mercenary Gall was saved by the high-ranking magician Kuon. Now, he's taken on the job of working with an order of knights to defeat a wizard! However, the knights are ambushed and easily defeated by the eldritch power of...Kuon?! Having survived the onslaught, Gall has only one option—accept a position as Kuon's apprentice, despite having no magical ability of his own!

(Source: Seven Seas Entertainment)