User blog comment:B214/Volume 23 discussion blog/@comment-86.143.86.100-20170203180136/@comment-31137559-20170204153732

Issei is fine with his demonic powers. The thing with the devil wings, I'm not so sure about that. But he has been able to transport by himself through a teleportation circle by himself since his training with Tannin. And he was able to cover his hand in aura to be registered as a king. So it hasn't been specified how much demonic power Issei has at the moment. I would say a normal amount. He did create Dress Break and Bilingual by using his demonic powers.