I'm not totally onboard with this. One of the reasons people like playing these sorts of games is because it feels great when you do something smart and win the game because of it. If the game is a little too "everyone's a winner!" it may diminish that positive experience and ultimately cause people to get bored of the game faster. In particular, I feel it is basically essential for your character to talk at least a little shit during a Yomi counter. You should feel like a genius any time you pull that off successfully.
However, I do agree that it's really important that if people lose, they know why they're losing and what they can do to improve, as there's nothing more frustrating than losing and feeling like there's nothing you can do about it. Various games have tried to come up with tools to help with this, for example in Persona 4 Arena every time you get opened up a little symbol shows how it happened, and games like Skullgirls have complex replay features intended to help you analyze various situations. I'm not sure exactly what would work best for Fantasy Strike. It's possible that the game is so simple that it might not take much. Maybe some kind of quick replay showing how you lost each round for some quick pattern analysis?
I'm not sure there's really any kind of sensible handicap system that can work for this game, due to how simple it already is. I was thinking of something like maybe giving the handicapped player faster meter charge, but then you'd be practicing under non-standard settings which might teach you bad habits for later. It's probably the intention of Fantasy Strike's design to make handicaps largely unnecessary by removing the execution barriers that prevent new players from being able to play effectively.