User blog comment:Jopjopjop/Volume 20 Spoilers/@comment-73.46.6.122-20150727175623/@comment-26209278-20150727190511

1) it's because she absorbed the excess dragon power from him.

2) It's assumed she does it off-story, but that she does it, not as much as Akeno i believe.

3) I think the dragonar armour is possible because they practised it with the wyverns, not because of the excess power inside of her. He may be able to do it with any of them, with practise, but im not sure on that.

4) I think her oppai beam is a result of Issei being a perv with magic power.