During the course of Severian's travels "Terminus Est" plays a vital role, alternately saving his life and placing it in peril. Shortly after leaving the Citadel of Nessus, Severian is caught in a ploy masterminded by Agia and her twin brother Agilus, designed to deprive him of his sword and belongings after he loses a duel to the disguised Agilus. "Terminus Est" is described as having been one of the last works of a famous swordsmith—so in addition to its inherent utility, it is also an antique; Agia describes it as being worth ten times the value of her shop and its inventory.