Toggle weapons in character selection screen
You can toggle backpacks, there is a check mark on the back item down in accessories. I use that with Mad King’s Memories so I only have a giant flaming book on my back when I need a light source.
I agree that being able to hide weapons would be very handy for RP. I would suggest that being in combat toggles them back on, though, to assuage those PvPers who want to be able to gauge likely attacks from their opponents.