User blog comment:B214/Volume 23 discussion blog/@comment-206.224.253.186-20170420231523/@comment-79.25.167.4-20170421231052

Exactly. Magic requires deep knowledge of calculation and Issei is not qualified to do that. He is smart, but not in that way.XD

Vali has an extreme talent in Norse Magic, only reading a book he was prepared enough to defend against Loki's spells. As we readi in EX Vali will become the first Devil Archmage (so this mean that he will be considered a monster even by the wizards that are considered monsters because of their incredible magic abilities XD), and that makes sense. Vali is very proud of his bloodline, but right now is too focus on his power alone. He said that he wants to become stronger only through his immense demonic power and his Sacred Gear, but that's an incredible waste of talent. I was very happy to read that in the future he finally made use of his magic talent, and that's make sense because that will be the best way to be able to fight equally or even defeat Ise when he will have awakened all powers he currently possesses (the fraction of Ophis and Great Red combined with Ddraig's and his own strenght).