@Nk9bjP4A He was as powerful as a seasoned Knight when he was a child and defeated an enhanced Minotaur as a student that even his whole class couldn't put a scratch on. Remembering martial arts from a past life, continuing that training while going to a noble school that trained him more, age progression, being contracted to a great spirit, plus years of training at the Village of Spirits put him on another level.
He's been powerful the whole time. But he also realized that using brute force would bring more problems than it would help solve.