User blog comment:B214/Volume 17 spoilers./@comment-117.217.186.212-20140224111716/@comment-24331253-20140301151844

I just thought about this;

Draigs hidden ability could be gravity control.

Well its just speculation since Rias's new technique (Extinguish star) is said to be like a black hole with immense destructive power from her power of destruction that pulls/sucks its opponent (e.g Grendel) towards the attack erasing them.