It would be nice if some vendors were able to repair weapons, because I don't think it's in the game at all now.
I could probably do something about this if you list the vendors best suited for this.
I think the guy on the second island, called "Arms dealer" would be a good choice.
Can you post some pieces of dialogue with him so I can recognize him?
He opens up with "Hey hey! I've been waiting for you for ages. Let's do some business, huh bro?"
Does anyone upgrade weapons?
All the vendors can upgrade weapons and you can do it yourself with a perk.
So the vendors can update a weapon but not repair it?
That's right. But it would be an appropiate window to add the feature to!
No, only repairkits for vehicles. That's too bad, but thanks for the effort!
Unfortunately there's no such perk in Xenus II.