Only for some players. My chars run staff / staff so having one on back and one in hands would be silly. See what I mean? That said, for sword / bow it could be cool. So. . . the answer would be a toggle option. I would never use it but you might well enjoy it it seems.
Wouldnt it be cool if your bow/quiver would be on your back if you had your sword in your hands, and vice versa? Also...weapon/quiver dying pls.
It cannot be since when we "sheath" our weapons they go on our back which would look odd if we had a stockpile of weapons on our back. Would also mean that visually we would not know what weapon was active when our weapon is sheathed without looking at the skills on our bar.