i think it's quite useless.. this because it will replace command 7 and 8 keys as said by another person and also because mainly ingame when u hit a 1 key it will drink a pot and put a new same pot in the 1st slot position.. which means that max u can need there is 1 for mp, 1 for hp, 1 for sun, 1 for gins and still u will have spair spots.. no?
i would ratherly think of using some of the belt slots for new features.. not sure what exactly but maybe someone can have some nice ideas..