Sword "Nothung" of Sigurd

Sigurd or Siegfried (Siegfried) is a hero of Germanic literature and mythology, son of Sigmund —rey of the Franks— and of Hjördis — daughter of Eylimi, who was born in a forest and died during childbirth. protagonist of the prose story the Saga Volsunga and the poem the Song of the Nibelungs. However, the variants of this legend are numerous, highlighting the origin of his literary appearances in the Eddas of Norse mythology, medieval Icelandic works: the Minor Edda, Edda de Snorri or Edda in prose, and the Edda Mayor, Eda de Saemund or Edda in verse. These two collections of ancient Norse tales make up the most reliable source of Norse mythology.
The oldest are the Eddas in verse. They are a collection of 34 Icelandic poems, sprinkled with prose dating from the ninth to the twelfth century. Most of these poems treat Norse mythology. After these Eddas in verse appear the Eddas in prose. It is the work of the Icelandic poet and historian Snorri Sturluson (1179-1241). This work contains the creation of the world, several mythological fables, an analysis of ancient poems and the rules governing prose. In them are, within the heroic chants, the first references to the history of Siegfried.
Siegfried and the dragon.
Siegfried grew up in the jungle and then had as a teacher the blacksmith Regin, who advised him how he should kill Fafner, the dragon guardian of the Nibelungen's treasure in Gnita's Heather. The future hero forged again the sword that had belonged to his father (Nothung or Balmung), and with it he pierced the heart of the monster, in whose blood he bathed to become invulnerable. Only one place on his back - where he had stuck a linden leaf - was not bathed in blood. The parallelism with the Achilles hero of Greek mythology is astonishing: Achilles became invulnerable by bathing in the Styx lagoon, and only on the heel (where his mother took him from bathing him) was mortal.