User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-3965848-20150517200407/@comment-98.227.238.52-20150518072305

Maybe Vali will find a way to unlock Albion's original ability Reflect. Issei managed to do it and he only had part of his power inside of him.

Also and this maybe a long shot what if Ise gave Vali one of Ddrag's jewels so he could take in some of his powers. If he work hard enough then he could probably unlock Ddrag's penetrate power which would allow him to bypass his grand fathers defenses.

And again this is a long shot considering Vali would most likely refuse as he is all about fighting using his own strength so I doubt that he would ever except something like that.

Also doing something like that does shortens ones life span. Though for someone like Vali that would be a small price to pay considering how much he loves to fight and he even said himself that he doesn't care about living to long.