Steel Barnacle

Uncommon, wondrous item (requires attunement) This warm fist-sized barnacle seems to enjoy being around metal. As an action, you may attach it to a metal weapon at any point of your choice, or remove it. Removal of the Barnacle leaves no damage on the weapon. While attached to the weapon, it gains the following benefits:

• The weapon becomes resistant to rust and similar effects, as the barnacle magically consumes any rust.
• This item contains 2 charges. When you hit a target using the weapon it is attached to, you may use a bonus action to cause steaming water to magically burst forth from it. Any creature in a 15 foot cone originating from you must succeed on a Dexterity saving throw (DC 14 or your DC, whichever is higher) or take 3d6 fire damage, or half on a success.