[Daisuke]

Is that any different from how it is now though?
There's nothing stopping you from selling a weapon with an inappropriate name and then saying someone else named it that. All a crafter's mark would do is give you a direction to point your finger, doesn't actually change anything since there's no proof in either case.

And dealing with that is pretty simple. If you go to buy a weapon but it has an inappropriate name, you don't actually have to buy it and you can just tell a GM and they make you rename the weapon. After that, if it's a reoccurring problem with that same person you'll be able to tell if they're trying to get away being immature. And if you buy the weapon despite it's name and it turns out to be a problem, you basically set yourself up for any finger pointing. Just tell the person "Hey, that name's not cool. Change it please" and if they're a reasonable person they'll do it. If not, it's not like you need to buy weapons from them anyway.