A lot of weapons would clip through the swords, then they'd also have to change the positioning of them on NPCs in storyline cutscenes.

Plus it makes a lot more sense to have heavy weapons (2h)/staves/shields/tools on the back, and lighter/1h weapons on the hips.

Not to mention that the fishing class stuff shrinks down for ease of carrying, and turns into a two handed tool when being used to fish. (Plus there's more 'wanted features' over something that's just a sheathed weapon change)