@AMetroid The problem of him being underleveled is
slightly addressed in the fight between the old man and the toothy dude. Also it's a game on the internet and let's be honest somebody would have figured out what a good weapon looked like within five minutes of opening Wikipedia (unless the game makes it impossible to open browsers in the MMO headset).
It's also worth noting that he only hunts starter level mobs and never goes any further.
Somebody else figuring it out on purpose would also only be viable if they had more to experiment with, and within the bounds of the story--where everyone else seems to really like min-maxed builds--that seems unlikely. The LN sheds more light on this with their BBS sections, where players gripe that not enough players have non-combat skills, but that's obviously not reflected here.
And as for his luck...I mean, he ends up with the one NPC that's designed to have some level of self-intelligence along with business practices that are probably in violation of showing favoritism, so...yeah, if we're complaining about this, we're gonna have to complain about the premise of the entire story, and that's a pain in the neck, so let's not do that.