Item from A Song of Ice and Fire by George R.R. Martin
A small, unassuming dagger of Valyrian steel with a dragonbone hilt — the weapon that started the War of the Five Kings and ended the Long Night, passing through more hands than any blade in Westeros.
This dagger has been the fulcrum on which the fate of Westeros has pivoted twice. First, when an assassin used it to try to kill Bran Stark in his sickbed — an act that sent Catelyn to King's Landing, triggered her arrest of Tyrion, and set the Starks and Lannisters on a collision course that killed thousands. Littlefinger claimed the dagger was Tyrion's, a lie that accelerated the war. The dagger's second moment came at Winterfell, when Arya Stark used it to kill the Night King — a single thrust of Valyrian steel into ancient ice, ending the Long Night in a heartbeat. The dagger transforms every scene it appears in because it carries the weight of both moments — it is simultaneously the weapon that nearly destroyed the Starks and the weapon that saved the world.
A slender dagger with a blade of smoky Valyrian steel, dark and rippled, set in a hilt of dragonbone. Small enough to be concealed, sharp enough to cut through White Walker ice. The blade has an elegant simplicity that belies its outsized role in history.
Also known as: the Valyrian steel dagger, the catspaw dagger, Arya's dagger, Littlefinger's dagger