If you're planning to sell spares as statless fuses to other players, you will need to get in-game equips that are tradable first. They're easily obtainable from item girl in paradise shop and other shops. You'll also need Artisan's Flames.
Fuse the item to the tradable equip and you'll be able to trade it to other players.
If you don't want to sell your spares, you can take them to the recycle machine which you can find in Mega shop. You can recycle your item for coupons which you can then trade for scrolls that boost your stats, cure yourself and others around you and prevent bosses/monsters from banishing you.