An Invention for use by an Inventor. It's a large spanner, the end of which is kept super-heated by some kind of special gizmobob, or something. It can be used as a fire-elemental physical attack on a single foe, which lowers defence. It also sometimes causes Numbness.
Thermal Spanner is an item in the MARDEK series. It can be equipped in the Weapon and Shield slots by Meraeador.