Neried Kyrie 1

Beelzebub-sama answered.

[Umu. She’s still lightheaded since her consciousness came back, so she hasn’t regained her memory yet. It’s safe to say that she’s still fuzzy. Also, about the special abilities of the new Longinus… It’s really dangerous. [Nereid Kyrie], it has two special abilities. The first is the power to make a Dragon powerless, or enslavement by her voice. The other one is controlling the sea. This is also troublesome. In other words, she can control a large group of Dragons, and even sink urban areas by controlling the sea. Depending on the way it’s being used, it is a Sacred Gear that can easily affect the world in a bad way. That’s why it’s categorised as a top-class Longinus.]

True DxD Volume 1, Life 3