The Soulsword is a fictional sword depicted in various Marvel Comics publications.
The Soulsword was created by Illyana Rasputin
during her imprisonment in Limbo by Belasco
. Illyana magically caused her own life force energy to manifest before her. Once this happened she cast her hand into a pool of eldritch energy and imagined a weapon in her mind. When she withdrew her hand she discovered she was holding the Soulsword, which was created from her own soul. A simple looking blade upon its origin, it began to develop intricate designs and forms upon itself the more Illyana used it, becoming more powerful with each use.
After Illyana's death the Soulsword was passed to Kitty Pryde who initially rejected it due to its ties to dark magic. It was then taken from her by Doctor Doom, and then taken from him by Darkoth the Death Demon. Amanda Sefton possessed the sword afterwards when she became a temporary ruler of Limbo. Fearing it would be stolen again, Amanda magically hid the sword inside the body of her former lover Nightcrawler.
Recently a resurrected Illyana Rasputin was seen aiding the New X-Men in Limbo, after Belasco abducted them and the adult X-Men to his realm. She is also responsible for using the soul of the New X-Man Pixie to create a soul dagger, a blade similar in origin, if not power, to the Soulsword.
The Soulsword has been shown to only harm magical creatures or objects – it rarely injures non-magical beings or items. The only exception to this rule has been the X-Man Kitty Pryde. It previously cut her while she was in her phased state. It can be used to counter/break any spells that might be on a person, or drive out possessing entities. The Soulsword can increase the mystical abilities of any magic-user, and as the Soulsword is the living embodiment of Illyana Rasputin, whomever owns the sword is considered to be the ruler of Limbo, just as Illyana once was.
The Soulsword has appeared in various dimensions, wielded by alternate Illyana Rasputins. For example, the Exiles version of Illyana wielded her own blade, which was referred to as the "Soul Sword of Bata's Circle." The exact origin of this sword is unclear, but this version of Illyana was able to create another blade after losing her original in a fight with Earth-616's Archangel.