User blog comment:Jopjopjop/Volume 18 Spoilers/@comment-93.105.244.248-20150521152159

There is a way for Vali to use Penetrate. But if Vali does that then he will probably sacrifice his life to kill Rizevim.

What I mean is he will ask Ise to give him one of his gems and implant it into his armour just like Ise did when they fought each other. More over it appears these lost skills require the power of both heavenly dragons to unlock. As despite being the strongest Hakuryuukou in history and having such talent he cannot unlock Reflect. Which is Albions own ability and Ise can use it while Vali so far cannot.

Well maybe Ise could lend him a Wyvern. But then again probably only the wyvern would be able to land hits.