Being able fuse, say, a desperado onto a gun or a bow onto a fan would be awesome, and would definitely open up many doors to new outfits for all classes.

Personally, and I believe many can relate, I sometimes feel like I'm confined to a certain range of outfits based on my class because my weapon can only look a certain way. For example, as an Hoyoung main, I'm stuck with using the tiny black line that is my Abso fan (all fans basically look the same), a transparent weapon effect that doesn't make too big of a difference, or an NX weapon from the CS. With NX weapons, they're mostly designed to fit a specific theme and most of them feel out of place when mismatched into a different outfit set. Not to mention most of the newer NX weapons have loud attack/jump animations, so for those of us who prefer a simpler aesthetic, it seems like a transparent weapon would be the best bet.

However, with the wide variety of appearances that non-NX weapons have, a cross-type weapon anvil would give players much more control over their outfits, as well as significantly expanding the number of possibilities for outfit themes. Do you like the ranger aesthetic but you're stuck as a warrior? Do you absolutely love the look of a DA's desperado (honestly look at those beautiful things), but you're a knuckle user? With a cross-type weapon anvil, you won't be limited to fusing the same old silhouette of a sword or a knuckle, and it would open so many doors to new outfit designs.

P.S. One potential conflict could be from Adele's bladecasters being invisible, which would turn any other weapon invisible when fused, essentially making the fusion anvil a transparent weapon effect. One solution would just be to prohibit fusing invisible weapons onto other weapons.

TLDR: A Fusion Anvil that allows players to fuse weapons of different types would allow a lot more freedom in creating new and unique outfits regardless of class.