Taken from a recent article in Dev Notes from the kGE website, it is one of the game features I have been wishing for years. And now that it's surely in the realm of possibility, I do hope it gets implemented as soon as possible. And when it does, I can cross it off my long Granado Espada wish list right above unique expert stances for Ramiro and Tiburon but below Healing/Cure being deactivatable.
The design are subject to change but at the moment, the new feature can be used by setting up a customizable list of left and right slots which can be equipped by either weapons or rings. You then can switch weapon/ring of the selected character by pressing Tab + Q/W/E/R/T/Y depending on your setup. You also have to have the corresponding weapons/rings in your inventory for it to work. It presents a quicker way of switching weapons and rings that would make life easier for buffers and raids with multiple monster races. The ui design and shortcut is being discussed right now but whatever they come up with, I think it will be a huge help to life in Granado Espada.