Ciel herself implied pretty heavily that she was created by Noah's abilities, if not outright stated it, though.
Well, the specific manifestation of "Ciel" that Noah can see and talk to probably was.
But, assuming Noah's magic works like Infinite's, I doubt the devil girl is the real "Ciel".
Of course that assumes Noah's spirit-thing is talking through her.
"If it lives it can be killed.
If it is dead it can be eaten."
Ronkong Coma "the way of the bookhunter" III Catacombium
(Walter Moers "Die Stadt der träumenden Bücher")