Durendal or Durandal (most likely from the French durer, "to endure") is the sword of Charlemagne's paladin Roland in the genre of literature Matter of France.

In The Song of Roland, the sword is said to contain within its golden hilt one tooth of Saint Peter, blood of Saint Basil, hair of Saint Denis, and a piece of the raiment of the Blessed Virgin Mary, and to be the sharpest sword in all existence. In the poem, Roland uses the sword to hold off a hundred-thousand-strong Muslim army long enough for Charlemagne's army to retreat into France.

More Info: en.wikipedia.org