@Bramia
You are trying to use REAL WORLD physics and logic to apply to a manga where this kid has taught himself to be proficient in martial arts to the point where he would be considered a master against a girl who was taught by a master and also had a natural talent.
Your lack of intelligence while attempting to use a form of intelligence to explain a situation that can possibly apply to the given situation is astoundingly stupid!! Then you look to attack me because you want to fit a square peg into a trapezoid-shaped hole.
Let's review the rules of that manga's world: everyone that's born is born with a job that can't change. The MC has exceeded the capability of his "non"-job status. He was able to teach himself martial arts techniques without a master and exceed techniques that a student with a job and master had learned from her master.
You couldn't get any dumber if you tried.