I'm not sure that this is even something that could be done in-game (it would introduce a couple of new complications at the very least), but I'd like to be able to further stitch dual-wielded weapons so that I'd better like the look of each weapon. For example, I'd like to use the staffy portion of the Gorgomancer's Set with the shooty part of Papa Screech's Set.
I's expect we'd be limited to choosing pieces only from same-type weapons, just as with stitching now (the above examples are both shooty/staffy weapons).