Christine Banner was the current apprentice of Battleaxe and the impostor Katana.
History[]
She was trained by Battleaxe to marshal the arts of the ninja as part of her plan to frame Katana for the mob bosses' murder. After completing her training, Christine disguised herself as Katana and went around murdering some of the mob bosses.
After visiting Battleaxe in her cell at Gotham Supermax Prison, Katana contacted Alfred for the information on Battleaxes's previous apprentices, Cheryl Dorne, Lai Kung and Christine Banner, and realised that any of the three women could be disguised as her. At that moment, the fake Katana appears behind the real one, and after a brief fight, the impostor knocks the real Katana off the roof into the river below. Thinking that Katana is dead, the impostor runs off, while the real Katana survived her fall and followed her to Tobias Whale's hideout, where they fought again. During the fight, Batman grabs the Soultaker Sword before the impostor can grab it during the confusion, leading to her escape.
After explaining to Katana about her impostor, Batman and Katana confronted her at her apartment, and learns that she was Christine Banner, and deduces that she fights with her left hand while the real Katana fights with her right hand, and hands her to James Gordon, who took her into custody, where she ends up at Gotham Supermax Prison in Battleaxe's cell.