User blog comment:B214/Question and Answers/@comment-24098614-20131121080854/@comment-68.210.8.41-20131121085303

Not necessarily. While it would be highly unusual, it is not impossible for what I'm proposing. Perhaps I should point out Kiba Yuuto - or Yuuto Kiba, whichever you prefer. In the story, Kiba became a noteworthy, living anamoly upon achieving the sub-species Balance Breaker of Sword Birth, the Sword of Betrayer. With this Balance Breaker, Kiba can create swords that have Holy and Demonic powers fused into them, in addition to Sword Birth's versatility. Aside from versatility, each Holy-Demonic sword would, in terms of raw power have over half the strength of the "True" Excalibur. In addition to this, the - supposed by product of this incident was Kiba being bestowed a Blade Blacksmith, the antithesis to Sword Birth. This effectively made him the first Devil on record capable of wielding a Holy type Sacred Gear - if not Holy weapons in general.

As for the subject of this question, while I agree with the possibility of a "pure" Angel taking in an Evil Piece could create an "artifical" Fallen Angel, there is another possibility, albeit slim. In light of the precedent that Kiba established, the kind of being an Angel is, as well as what an Evil Piece is and what it does, what if - and I emphazise "if" - create an "artificial" Nephilim? That is to ask, what if the combination of an Angel with an Evil Piece creates a Nephilim not unlike Dante and Vergil from the new "Devil May Cry" video game? Still, a concept such as this is theoretical at best and typically will remain such until it's proven or been put into the story. But for what it's worth, I think it is possible. After all Kiba - and his first Sacred Gear - are liing proof so to speak.