I like to play around with a bunch of different classes before choosing the one I like best. That means I've got a lot of gear that I use in sets. I can't tell you how many times I've been going through trying to make space by turning stuff into materia, or selling off to NPCs and accidentally discarded something I was still using because there's nothing but my own memory to tell me if I'm using a piece of gear in my inventory for a set or not. Could we maybe get a sort of mark on the icon for gear pieces that let us know we have that piece saved to a set, or perhaps have NPCs ask if we're sure we want to sell (or the game ask if we're sure we want to make a materia) since that piece of gear is currently saved to a set? It would make things a heck of a lot easier.