I never said he was good at it, was never the point of my comment, i just said based on what was he bad? He literaly had to fight super humans, his sword even broke when he hit him. Even if he was good at it, he wouldn't be able to compete with his siblings, cause they had passed the strength of trained soldiers already.
So i ask you again, based on what was he bad?
His whole backstory was to show that he was behind his siblings, not that he was bad at things. The fact that he trained would make him stronger and put him above the average kid anyways, it's just he couldn't compete with his siblings.