User blog comment:B214/Question and Answers 6/@comment-99.235.66.221-20161130072057/@comment-9595671-20161214135550

In fact, I think their additional abilities after they sealed their original powers were the results of who gained the advantage in their fights. if we use Ddraig being more about strength and Albion as more of a tactician, here's how I see their powers developing.

Albion fights tricky, so Ddraig wanting to hit harder to take him out faster creates his [Boost] ability. In response, Albion then creates [Divide] to regulate how strong Ddraig's boosts can become, but at the same time Ddraig's boosts affect it's strength.

In response to that, Albion creates [Reflect] to use against some of Ddraig's attacks when Divide ins't enough, and Ddraig likely ends up getting so annoyed by it that he creates [Penetrate] to smash through the ability, and then it just keeps going from there.

This is probably also why Vali was the one initially stronger, by being stronger he gave the right triggers to push Issei in the right way for him to get stronger. Had someone else been the White Dragon instead of Vali, I honestly think Issei wouldn't have gotten as strong as he is now.