Scell is a Promethium soulsword. Holding it, Nemesis is the living embodiment of the spirit of retribution, the full extent of her abilities were never stated. Being technically "dead", Nemesis body continued to function strictly as a result of her physical connection to the Scell. Since Nemesis' second death, the fate of the sword is unknown.
Flight: Her sword granted Nemesis the ability of flight, however, it was never stated how fast her top speed while flying was.
Longevity: Scell allowed Nemesis to live an extended life, using the life force of those she killed. Her current age is not known, but apparently she has been to hell twice. She was shown to be an adult in Chicago during the Prohibition as well as being around during World War One. It is not known how long she had been alive prior to this era. Also, as stated by Nemesis it was not required for her to eat in order to survive.
Speed: Nemesis possesses superhuman speed, enabling her to easily evade multiple gunshots while she was flying as well as showing such speed that she could cut Deadly Ernest into multiple pieces in a blink of an eye.
Teleportation: The sword grants Nemesis or others of her choosing the ability to be teleported to her desired destination,. This ability was never fully explained, nor were its limits.
Time-Travel: Nemesis was able to use her sword Scell to open portals through time. However, in order to do so, she requires a blood sacrifice of one who has been to the timeline in question. Nemesis stabs the one person for the destined time and then another time to send that person back.