General

after u fuse them u keep the item u used as the appearance but the function one gets used up

If i had a fusion anvil, i would get a pro terminous sword and make it look like a lvl1 sword

So if i use specs as apperance and kenta as function, i get both items back but now the kenta looks like specs?

Also you still get to keep both items. It doesn't switch the appearances either, it just copies the appearance of one item onto another

Takes the appearance of one item and places it on another.
So you can take the appearance of Spectrum Goggles and put it on your Kenta Goggles to make them look like Specs.