A sword used by the protagonist, Corwin, prince of Amber, in the original Amber series by fantasy author Roger Zelazny. Eventually, the sword is used by Corwin's son, Merlin.
The sword, as a weapon of Amber presumably has some magical abilities, but they do not make a big difference in the course of the books, as the Princes of Amber (and Princesses) have sufficient powers of their own.