What's up with the grade ranking?, And how the hell do i get a good one? Options

[Crushinator]

What exactly determines how high your grade is at the end of a fight? The highest I've been able to achieve so far is B+, and that was on a battle I didn't feel went too well. On some battles where I take NO damage at all, and don't lose any cards, I only pull a C or C+, even if I totally decimate the opponent.

Is there some secret "style" guage in the game that rewards using good combos or something, or is it based on the types of cards you use (strong ones, or weak ones???). It doesn't make any goddamn sense. And how the hell am I supposed to get better cards when you can only get a good score using good cards (WHICH I DON"T HAVE!!!)???

[Vitamin D]

I've gotten an S ONCE with Saligun. And I thought the match was a disaster, so I know exactly what you mean. And the highest I've gotten with Arkz I got with Hyze, an A+. That match took a REALLY long time (I was fighting Guykild...) so yeah, i have NO idea how the ranking system works either. I'd sure as hell like to know though haha.