Cloak of the Eel

While wearing this rough, blue-gray leather cloak, you have a swimming speed of 40 feet. When you are hit with a melee weapon attack while wearing this cloak, you can use your reaction to generate a powerful electric charge. The attacker must succeed on a DC 13 Dexterity saving throw or take 2d6 lightning damage. The attacker has disadvantage on the saving throw if it hits you with a metal weapon. The cloak can't be used this way again until the next dawn.