User blog comment:Jopjopjop/Volume 20 Spoilers/@comment-204.112.39.65-20150823010144/@comment-1359322-20150824044412

Not really possible. Kiba was able to create the Sword of Betrayer because of his friends' spirit combining with his Sacred Gear, even then it doesn't eliminate the weakness he has towards Holy powers, if he's strike with Holy powers he'll die. Even Asia and Xenovia who can pray is effected by the cross.

So no Devil up to date can combine Holy and Demonic power in their body. Well maybe Ise and Irina can succeed by giving birth to their child.