Elric and Stormbringer kill Yyrkoon, and no further mention is made of Mournblade until it is later disclosed that it was recovered by the Seers of Nihrain, to be wielded by Elric's cousin, Dyvim Slorm. Yyrkoon has regained Mournblade through unknown means and uses it to attack. In The Weird of the White Wolf, Elric returns to Imrryr after a long journey and confronts Yyrkoon, who usurped the throne in his absence. Yyrkoon is defeated, and Elric and his cousin return to Imrryr. Elric and Stormbringer disarm Yyrkoon, and Mournblade disappears. In Elric of Melniboné, Elric and cousin Yyrkoon find the runeblades in a realm of Limbo and commence battle. Three such sibling blades appear in The Revenge of the Rose and many more 'brother blades' are seen in the novel Stormbringer, but only Mournblade and Stormbringer are named. Later stories reveal that there are thousands of identical demons, all taking the form of swords. It is identical to Stormbringer in most regards. Stormbringer has a 'brother' sword named Mournblade, which was at one time wielded by Elric's cousin and enemy Yyrkoon.

The cursed nature of the sword adds to Elric's guilt and self-loathing, even as he feels pleasure when the stolen lifeforce enters his body.

Stormbringer's hunger for souls is such that it frequently betrays Elric by creating a bloodlust in his mind, turning in his hands and killing friends and lovers.

Elric loathes the sword but is almost helpless without the strength and vitality it confers on him. Its most distinctive features are that it has a mind and will of its own, and that it feeds upon the souls of those it kills. Stormbringer's edge is capable of cutting through virtually any material not protected by potent sorcery, and it can drink the soul from (and thereby kill) any unprotected living creature upon delivering any wound, even a scratch. This powerful enchanted black blade is a member of a demon race that takes on the form of a sword, and as such is an agent of Chaos. In the four novellas collected in the 1965 book Stormbringer, the sword's true nature is revealed. Stormbringer makes its first appearance in the 1961 novella The Dreaming City. It is wielded by the doomed albino emperor Elric of Melniboné. It is described as a huge, black sword covered with strange runes, created by the forces of Chaos with its own will. Stormbringer is a magic sword featured in a number of fantasy stories by the author Michael Moorcock.

Son of a black sword