Ah, Michael Moorcock's Eternal Champion. To be honest I never actually read anything other than the Elric novels, and not even all of them. These books are good, old fashioned, swords and sorcery hack and slash adventure. They are a bit unusual in that the hero of the stories isn't really so much a hero, or even an anti-hero. He's an anemic albino kept alive by the sorcery, heir to a corrupt and decadent kingdom that he helped destroy. In short, Elric of Melnibone is a mess. Then there's his big black sword, Stormbringer.
Having helped destroy his homeland Elric can no longer get the potions needed to keep him standing, now he has Stormbringer for that. Stormbringer is a rune sword powered by Chaos that consumes the souls of it's victims to sustain Elric's strength. Not a few of which are Elric's friends. It may come as no surprise that Elric is a brooder.
This is one of the few vintage Elric covers I have. Elric seems so at peace while Stormbringer sucks out the soul of his victim and feeds a portion of it to him so he might exist another day.