Tyrfing, Tirfing or Tyrving (The name is of uncertain origin, possibly connected to the Terwingi) was a magic sword in Norse mythology, which figures in a poem from the Poetic Edda called Hervararkviða, and in Hervarar saga. The name is also used in the saga to denote the Goths. The form Tervingi was actually recorded by Roman sources in the 4th century.
Svafrlami was the king of Gardariki, and Odin's grandson. He managed to trap the Dwarves Dvalinn and Durin when they had left the rock where they dwelt. Then he forced them to forge a sword with a golden hilt that would never miss a stroke, would never rust and would cut through stone and iron as easily as through clothes.
The Dwarves made the sword, and it shone and gleamed like fire. However, in revenge they cursed it so that it would kill a man every time it was drawn and that it would be the cause of three great evils. They finally cursed it so that it would also kill Svafrlami himself.
When Svafrlami heard the curses he tried to slay Dvalin, but the Dwarf disappeared into the rock and the sword was driven deep into it, though missing its victim.
Svafrlami was killed by the berserker Arngrim who took the sword in his turn. After Arngrim, it was worn by Angantyr and his eleven brothers. They were all slain at Samsø, by the Swedish champion Hjalmar, and his Norwegian sworn brother Orvar-Odd; but Hjalmar, being wounded by Tyrfing, has only time to sing his death-song before he dies, and asks Orvar-Odd to bring his body to Ingeborg, daughter of Yngvi at Uppsala.
Angantyr's daughter, Hervor (by his wife Tófa) is brought up as a bond-maid, in ignorance of her parentage. When at last she learns it, she arms herself as a shieldmaiden, and goes to Munarvoe in Samsø, in quest of the dwarf-cursed weapon. She finds it and marries Hofund. They have two sons, Heidrek and Angantyr. Hervor secretly gave her son the sword Tyrfing. While Angantyr and Heidrek walked, Heidrek wanted to have a look at the sword. Since he had unsheathed it, the curse the Dwarves had put on the sword made Heidrek kill his brother Angantyr.
Heidrek became king of the Goths. During a voyage, Heidrek camped at the Carpathians (Harvaða fjöllum, cf. Grimm's law). He was accompanied by eight mounted thralls, and when Heidrek slept at night, the thralls broke into his tent and took Tyrfing and slew Heidrek. This was the last one of Tyrfing's three evil deeds. Heidrek's son Angantyr caught the thralls, killed them and reclaimed the magic sword, and the curse had ceased.
Angantyr was the next king of the Goths, but his illegitimate half-Hun brother Hlod (or Hlöd, Hlöðr) wanted half of the kingdom. Angantýr refused, and Gizur called Hlod a bastard and his mother a slave-girl. Hlod and 343,200 mounted Huns invade the Goths (See The Battle of the Goths and Huns). The Huns greatly outnumber the Goths. The Goths won because Angantyr used Tyrfing. He killed his brother Hlod on the battle. The bodies of the numerous warriors choke the rivers, causing a flood which filled the valleys with dead men and horses.