Double-Bladed Axe: Belvaac is an axe Teigu that can only be wielded by someone with a very high level of strength. It was formerly owned by Daidara and is currently owned by the Revolutionary Army. Anyone can carry it as long as they didn't use it as a weapon or Teigu.
While searching for a compatible weapon, Belvaac was one of many Teigus to be displayed by Honest for Esdeath to choose. Esdeath was quite fond of the axe, but had decided that it wasn't the perfect weapon she was seeking. Sometime after, Daidara got a hold of the Teigu and used it in many of his battles while fighting alongside his comrades. After his death, Najenda secures the Teigu and she can easily carry it since she's not using it as a Teigu before she took it to the Revolutionary Army Headquarters. It was later used by an unamed revolutionary soldier during the war.
In the anime, one of the revolutionary soldiers used it in a battle against Esdeath shortly before being killed by the General's ice power.
It contains a tremendous amount of offensive power. It looks like a double-edged axe, and it can be separated into two axes that can be thrown and will pursue the target until it hits.