Fuse is an entirely new mechanic in The Legend of Zelda: Tears of the Kingdom that offers near limitless potential. While weapon degradation has made a return, you can Fuse weapons with items (or other weapons!) on the fly to create more powerful versions of your on-hand armory.
You will earn this ability fairly early on during your time on the Great Sky Island, Tears of the Kingdom’s introductory area. It rules. Here’s how it works — and how to reverse it by finding some to Unfuse your items.
How to Fuse weapons and items in Zelda: Tears of the Kingdom
After you obtain the Fuse ability, the world is your oyster. Holding down your left bumper will pull open the radial menu, which you can then use to select the Fuse ability.
You can Fuse just about anything together, including rocks onto sticks, swords, and spears to create hammers — which can then be used to break rocks to obtain flint, amber, diamonds, and more. You can also Fuse items to arrows for various effects; Keese eyeballs, for instance, create homing arrows. You can even Fuse produce, like Hylian tomatoes, to spears and swords (but I wouldn’t suggest it since those food items can be used in better ways and don’t actually offer any kind of major damage boost.)
Interestingly enough, you can also fuse these rare minerals onto weapons to grant them magical effects — for instance, attaching a ruby to a weapon will allow you to shoot fireballs that will bounce off of surfaces. Additionally, some weapons work better with certain materials than others. This includes Zonai weapons. For instance, if you manage to find the hilt of a Zonai weapon and Fuse it with a material from a Zonai Construct, the weapon itself will get a bit of a boost.
How to Unfuse weapons and items in Zelda: Tears of the Kingdom
That said, you can really stick anything and everything together — and thankfully, Fusing isn’t permanent. If you find yourself using a rare material like a diamond on a stick by accident, you can actually detach the two, preserving both materials. This can only be done once you complete the Great Sky Island, however.
Once you’ve made it to Hyrule proper, you can take the very long trek to Tarrey Town, on the east side of the map. If you need a convenient fast-travel spot, the Rasitakiwak Shrine is just southeast of Tarrey Town. (You do not need to complete a shrine to activate its fast-travel spot.)
In Tarrey Town, head over to Pelison, the Goron child in the city square, to Unfuse your weapons and get those precious materials back. It will cost 20 rupees to Unfuse any weapon. This is also the only way we’ve found so far to Unfuse weapons while keeping the Fused item intact, by the way. You can’t just shake them apart as you can with any creations you’ve made using the Ultrahand ability. So while fusing isn’t permanent, it can cost a hefty toll if you don’t keep track of what you’re slapping together.
That said, if you’re not too attached to whatever you’ve combined, you can always go into the item menu, select the weapon you’ve Fused, and select the “Destroy Fused Material” option. This will demolish the item attached to the weapon you’ve used as a base, though, so keep that in mind before resorting to this method.