This article needs additional citations for verification. (April 2022)
The Tyrfing Cycle is a collection of Norse legends, unified by the shared element of the magic sword Tyrfing. Two of the legends are found in the Poetic Edda, and the Hervarar saga can be seen as a compilation of these legends.
The forging and the curse
The first part deals with the forging of the sword Tyrfing by the Dwarves Durin and Dvalin. They are forced to do so by Svafrlami, the king of Gardariki, but in revenge they curse the sword so that it will kill a man every time it is unsheathed, cause three evil deeds and be the undoing of Svarflami.
The Battle on Samsø
The second part deals with the legend of Hjalmar, Orvar-Odd and the duel on Samsø. Arngrim's twelve sons meet Hjalmar and Orvar-Odd in a duel, but the outnumbered heroes kill Arngrim's sons. However, Hjalmar has been wounded by Tyrfing and dies.
The fourth part deals with the saga of Heidrek the wise, the king of the Goths, and contains the riddles of Gestumblindi. If the killing of Hjalmar may be the sword's first evil deed, its second is the accidental slaying of Heidrek's brother Angantyr. The third and last evil deed is probably when Heidrek's slaves murder Heidrek during an expedition in the Carpathians.