My bets are on a curse, too many inconsistencies with his background that power house characters find him odd, the "disgusting.. gonna disappear" line in chapter 2 is what tipped me off, I think when he got bisected by the slime and they healed him they weakened the curse enough for him to start gaining some skills.So the weakest boy is actually the strongest in disguise due to some hidden skill that makes him grow his skills fast. Hm.
Knowing his masters, they'd probably like that.Ooh is he going to surpass his masters one day
Maybe, maybe not. What if, having a class actually limits you to that classes abilites/expectations? By being classless, he does not have said limitations.So the weakest boy is actually the strongest in disguise due to some hidden skill that makes him grow his skills fast. Hm.