I think you’re taking exactly the right approach for the Marketplace. If I need a skull encrusted axe, I probably have a lore reason behind it so I’ll want to have it custom made anyway.
But if I just need a dozen swords for as many knights, chances are I’d want just one looking sword model. If I had two factions that needed to seem different, two different sword models (or two different kinds of blades in general) would be the right way to go. Beyond that, swords can and probably should all look but nice.
Big fancy stylized swords are going to stick out to players. They’re going to notice if two games have the same golden flaming sword encrusted with rubies. But few players will notice a sword matching another game’s sword unless they play those two games back to back.
Firearms are probably this to a further extent. I don’t need a 1911 model that looks different from every other 1911 model in every other game, there’s no point. It’d be counter productive. What I do need is a 1911 that looks like a 1911, has enough moving parts for what I need, and looks nice.
So if you’re looking for a pack after this, modern firearms would be a great way to go. Though like I said, they’ll need moving parts for most games, and different games will need different amounts of moving parts. Could complicate things a bit, I don’t know, I’m no 3D artist. 