User blog comment:B214/Question and Answers 6/@comment-99.235.66.221-20161130072057/@comment-26821288-20161214120711

I actually think that this whole comparing Issei and Vali thing is really invalid. I mean, they are polar opposites, like their SGs are. Issei is supposed to be a power idiot, like Ddraig basically is. And look, what are Ddraig's abilities? [Boost] - doubles his own power. [Transfer] - give power to an ally. [Penetrate] - just smash any defenst the opponent may or may not put. And there's the fire thing, which is basically... roasting the opponent, as long as it's not GR, Ophis, or Albion. It's all about just smashing the enemies, and helping teammates.

While Vali is the exact opposite. He is much more of a tactican. [Divide] - divides the power of the opponent, making him gradually weaker and weaker. [Reflect] - reflect the attack you touch, which can pretty much either change the direction of your attack in case your opponent tries to go in a different direction, or reflecting the attack your opponent sends towards you, making his attack invalid. And there's the poison thing, which basically also weakens the opponent. And it's clear that he is much better as a lone wolf, rather than being with a team.

Exactly polar opposites. A power idiot vs a tactican. Ally-friendly vs lone wolf. Smashing through vs reflecting. You can't just compare them, they are polar opposites. It makes a whole lot of sense that Issei doesn't have a good control on his Demonic Magic, or even has a good amount, because he doesn't need magic, he's supposed to be a power idiot, to just smash through and nullify any defenses that may or may not be put, and as for the magic, he is supposed to be with a team, it has much more compability with a team, rather than being alone, so someone else can handle the thing about the magic. While Vali needs a vast amount of Demonic Magic, and a talent, as well as good control over it. Because he is supposed to be a tactican, do sneaky things, he is supposed to be alone, his powers work that way.

Though, again, it's pretty much just what I think about this. Like I said in the beginning of this comment, I think. Correct me if I'm wrong.