Akua Ringu

 Akua Ringu (アクアリング, Aqua Ring) is one of the seven legendary rings forged by using a legendary wolf spirit. Its main ability is Tranquility, it also allows the user to open aqua type boxes. It takes the form of a ring which emitts a blue flame when ignited using spiritual energy.

Powers
Tranquility: This ring allows the ability of tranquility, which means the user can use the ring to ignite his weapons and fist, so that whenever the user makes contact with the opponent it makes the opponent feel dizzy and suddednly drained of all their energy.

Aqua Box Unlocking: This ring allows the user to open aqua type boxes. This is the only ring which can open aqua type boxes as it was the only aqua ring made.

Behind The Scenes
This was based off of Katekyo Hitman Reborn's seven elements.