So normally my TWF uses two GS scimitars, but there are times that I run across an enemy that is immune to the "special effects" of one of them, e.g. Sorjek is immune to lightning damage, so my Lit II isn't all that helpful.
In situations like that, I am opening my inventory and switching out the less useful weapon for something else (holy, cursespewing, etc).
I would like to be able to switch out just one weapon from the hotbar, rather than needing a dozen different weapon sets for every possible combination. Perhaps a change so that having clicking a one-handed weapon on the hotbar would equip it to your main hand, but shift-clicking would equip it to your off hand.