Situation: Item or weapon in hands. New item double clicked from inventory, item currently in hands is dropped to the floor, as expected, and the new item occupies the hands. After the new item is put back, the item that was dropped to the floor is unable to be picked up. Dragging it to your hands does nothing, although you can re-log AFTER dragging it to your hands to get the item back.

You can drag the item from your hands to the vicinity BEFORE putting another item in your hands, and this will let you pick the item up again when you want to.