A quick price comparision of Empress eq between worlds.

the reason why capes and weapons are expensive is solely due to the fact of availability.

empress and her followers drop pretty much everything EXCEPT for the capes(exceptions for thiefs, ekhart does drop it i believe, making thieves the easiest for set) and weapons, which are obtained from older gachapon, wheel of marvels, actually crafting the recipe or events(or by duping).

Or, you know, you could get the weapon simply by killing empress. Which is what most people do to get weapons.