Soul Edge was originally created by human hands. At first, it was just an ordinary sword, but after being bathed in blood and hatred countless times, the sword turned into a demonic weapon and gained a wicked soul called Inferno. Those without strong wills are unable to escape the curse of its evil powers, as its spirit invades the mind like a parasite and drives its wielder mad. Its single eye burns fiercely with the regret of lost souls, but its blade shines with an icy gleam. It is evil to its very core.
The first known bearer of Soul Edge was a king, whose strong will conquered the malign intelligence of the blade. However, his son was not so strong, and quickly fell under the influence of Inferno. Jealous of his father's power, he stole Soul Edge and instantly came under the possession of the evil sword. In a desperate battle against the deranged prince, the mighty king defeated Soul Edge, but at the cost of his son's life. Swearing vengeance against the cursed blade, which disappeared after the encounter, he forged from purified fragments of Soul Edge the holy blade Soul Calibur.
The second known bearer of Soul Edge was Zasalamel, during one of his many lifetimes. Trying to break the curse of his eternal reincarnations, Zasalamel obtained the cursed blade, but instead, his soul was possessed by the evil will of the sword, and he turned into the host of the blade until the end of that life. After that, record ceases until several hundred years later.
Then, in the 16th century, Soul Edge mysteriously appeared once again in a secret antique auction. While it is unknown why it now existed as two blades instead of one, the evil spirit of the sword could not be mistaken. The swords were obtained by an English curio dealer, whose ship was attacked by the dreaded pirate Cervantes. Possessed by the will of the wicked swords, Cervantes slew the crew of the ship and then slaughtered the population of a Spanish port-town, where he stayed the next twenty-five years, waiting of the birth of the "Child of the Cursed Sword". But then a holy warrior sent by Hephaestus, Sophitia, confronted him and was able to destroy the smaller of the two blades. About to kill her, Cervantes was stopped and killed by a demon huntress named Taki, who helped the terribly wounded Sophitia home.
It was at that point that Siegfried Schtauffen, a young German knight, arrived seeking the legendary Soul Edge. When he tried to take the blade lying beside the dead Cervantes, Inferno, in an attempt to restore itself, flowed into the corpse and fought Siegfried for the possession of the evil sword. Siegfried won that battle, and when he grasped the hilt of Soul Edge, he was unable to control its power, and released the Evil Seed on the world.
Soul Edge now had a bearer worthy of its taint - Nightmare. Completely consumed by the sword, Siegfried went on insane killing sprees, murdering without distinction to feed the evil blade. By absorbing souls and gathering fragments of Soul Edge, the cracks in the blade began to heal. It was almost complete when two brave souls, Kilik and Xianghua stormed Ostrheinsburg Castle. After a vicious battle, Nightmare lay defeated, and Xianghua used Soul Calibur to shatter Soul Edge. But due the abyss created by the destruction of the void created by Inferno, both swords and Nightmare were sucked into it. Siegfried awoke on a different place, now free of the control and with the realization of his multiple slaughters.
Siegfried was himself again, but the effects Soul Edge had left on him were strong. Every time he slept, Siegfried would awake to the corpses of those he had slain in the night. Gradually, he slipped into Nightmare once again, and began reforging Soul Edge. After succeeding in restoring many of the sword's original powers, Nightmare was challenged by a swordsman searching for the legendary blade, Raphael. Their battle was intense, but Nightmare stood victorious in the end. With his last strength, Raphael made a desperate attack, and managed to strike his sword into the very center of the cursed blade. Screaming in agony, Nightmare fell back, and within his mind, Siegfried reawoke. After a fierce mental struggle, Siegfried regained his sanity. Suddenly, shining from the core of Soul Edge, the holy sword Soul Calibur appeared to him, released from its entrapment within the evil blade. Taking Soul Calibur, Siegfried drove it into the cursed blade, piercing the eye and silencing the power of Soul Edge. However, it was not enough to destroy the cursed sword, and now both blades lay locked in an embrace, seemingly annulled of all power...
Inferno, thrust out of Soul Edge by Soul Calibur, transferred itself into the remnants of Nightmare's armor, but could not manipulate the bodiless husk. It is then that a strange man named Zasalamel appeared. Agreeing to help Inferno if it assisted him in finding the two swords of legends, Zasalamel used his ancient powers to bind it to the armor. At this moment, the evil spirit of Soul Edge became the new Azure Knight. Born from the memory of its old shape, the Phantom Soul Edge is dwarfed by the real cursed sword, but as Nightmare once again began his quest to search for his missing form, this weapon began to grow stronger.
The real Soul Edge, silent with its counterpart Soul Calibur, was now in the possession of Siegfried Schtauffen, seeking a way to seal the evil sword forever.
Even if Soul Edge is seemingly powerless, there are still many of its fragments scattered throughout the world, expanding Soul Edge's influence far beyond the sword itself. Notably, Cervantes de Leon carries another version of the cursed sword, born from fusing several fragments together. Even though the sword was sealed, its fragments still emit the evil energies of the cursed blade.