Bow

Ciel's alias within the Burial Agency.
The name comes from the fact that her Christian name is Ciel, and she's the only person in the Burial Agency that fights using firearms.
…Well, it was also due to the scenario director's foolish blunder.
He knew that “arc-en-ciel” meant “rainbow” in French, but he mixed up which word meant what, hahaha.
He only noticed his mistake a little bit before the Half-moon edition went on sale, when he was listening to a song by a certain band.
The song was titled “ciel,” and was about the sky.
Honestly, it was kind of irritating, but at that point the scenario was already complete, and changing Ciel's name so late into development didn't feel right. In the end, he just tried to push through and finish without thinking about it too much.

Tsukihime Data Collection: Tsukihime Dictionary
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Ciel's alias within the Burial Agency. The name comes from the fact that she's the only person in the Burial Agency that fights using firearms.
It seems that Ciel is something of a gunpowder maniac, and the entire reason she changed the Seventh Holy Scripture into its current form was just to fit her own personal tastes. …Sure, shooting a gun feels nice and all, but I'm a little worried about her. I wonder if there's something strange at work stressing her out…?
Also, in Melty Blood she finally demonstrates skills worthy of this name. So many black keys…

Tsukihime Dokuhon Plus Period: Tsukihime Dictionary Revised