Mithril Treasure Items can be crafted at the Blacksmith in Bree. When forging any item there, two rings will appear, one inside the other. There will be with letters or controller buttons floating toward the center which you must press as they enter the rings. In order to make a Perfect Mithril Treasure Item, you must push each button or key as it floats over or within the inner ring. Do not worry if you make a mistake. Once you create a Mithril Treasure item, it will remain unlocked and can be reforged for free.