Hihiirokane

Hihiirokane is Tomonori's weapon, he used it against Yuki Terumi in Phase Shift 1.

Abilities.
Hihiirokane is unique in the fact that it has one ability that easily makes it more than a pair of swords: It can cut through souls as well as bodies, how it can do this is unexplained but because of the era it first appeared in, it can be assumed to be a form of Ars Armagus. The only known weapon that would also, under technicality, have this ability would be the Nox Nyctores - Mucro Somnio: Musashi because of its ability to cut through anything.

Appearance.
Hihiirokane appear as a set of two small kodachi (Japanese short swords) with small, thin black and brown handles and thin curved blades. Unlike a lot of other weapons in the series, Hiihirokane isn't very unique in its appearance.

Trivia.

 * It is unknown what happened to Hihiirokane after Tomonori's death at the hands of Terumi.