Mähne is a double-bladed long sword used by the Imperial cavalry. It comprises of two large blades joined by a common hilt with an extending holder. It doesn't get obstructed by the horse's head in terms of swinging.
Alice inherits Mähne from her grandfather, who served in the war. She is efficient with it and brings it along with her while facing the sewers refugee transporting mission. She carries it in a large wrapping case and uses it to fend off Claymore I from committing mass murder in the sewers. With Alice using her sword with deadly efficiency, even though she was tired, the vice-captain of Claymore I steps up to challenge her. He's able to avoid her attacks and lunges at her when she gets her sword stuck in the ground, but Alice does a spin and kicks the sword up with the heel of her shoe. This cuts through the vice-captain's mask and a subsequent slash finishes him off.