Like so. Not unlike the vials.
I would like this feature because I can't always keep track of what I put in which weapon slot and that could be handy to know in the middle of battle. The currently selected weapon has a little highlight so you can know what's getting selected when pressing the next and previous buttons.
This'd be in OOO's best interest because I'm sure I can't be the only one derping with this and it'd encourage me to sustain more weapon slots if this was added.
Maybe not exactly like that, it takes up a little too much space. but +1 regardless.