I'm more or less only asking for character sprites that already exist in the game to be applied to or changed for existing gear. I don't really see how this would represent a significant increase in the amount of system resources the game would require - we're not talking additional sprites being loaded simultaneously, just different ones.
This doesn't work as you think.
When we talk about how some character looks like, it needs own sprites created, even if you talk about already existing graphics elsewhere.
To be applied to character outlook, it needs sprites created for that outlook. And we talk about all things, wielding sword, axe, whatever, all animations, etc.
I know you look at 3D games and see that each item is applied to character, but this is 2D game and it needs sprites created for character outlook independently from items.
In 3D games, you just apply skin to 3D object and that's it. In 2D, you need it created, rendered and included in set. And in 3D game engine does that, in 2D it is done outside game, by authors and included in game sprites, which asks for memory.