The Gauntlet of Rust has the ability to rust any metal known to man simply by contact with that metal and water at the same time.
The party found the Gauntlet in Castle Greykin. It was being used in it's torture chamber as a means of torture. The castle's workers would place their victims in a suit of plate-mail with this gauntlet composing one of it's parts. The victim would then be placed in a Brazen Bull to be baked alive.
Many people died with the key to their freedom lying on their right hand.
Use in The Vault
It is used to melt down the barrier of metal surrounding Items in The Vault.