Alter Item
With your crafting skills you can alter equipment that gargoyle characters normally cannot wear so that gargoyles can use it. Not every piece of equipment can be altered for gargoyles. As a rule, artifacts and other named items cannot be altered.
To alter an item, double-click your craft tool to open the crafting menu, choose the "Alter Item" option and then select the item you want to alter. You must be a grandmaster of the crafting skill required for the conversion, and you also have to be standing next to a Soul Forge.
NOTE: Once you alter an item, it can never be returned to its original form.
Alterations can also be done with the help of a contract.
Alteration contracts work much like repair contracts. After opening the crafting menu and choosing the "Alter Item" option, select a blank scroll and you will get an alteration contract. You must be a grandmaster in the related crafting skill to make an alteration contract.
Source: Quinqis UO