Well there are three simple ways of kinda doing that. The first would be to make using magic take time, perhaps by charging it up or something. That way you sacrifice time you could be attacking be preparing your magic. The second way is to give magic cooldowns, a-la MMO abilities. Then finally you could simply make magic no more powerful than an attack, so there's no motivation to spam it. Or perhaps it does a certain type of damage (so you'd use it instead of an attack in certain situations).
There's more interesting stuff you could layer on top of that, but those are what come to mind off the top of my head.
Seems pretty likely it'll be something along these lines, I agree.For some reason this makes me think of FFIX. Steiner, a non magic user, can use Sword Magic while Vivi is in the party. Maybe Noctis can share his magic in a similar way, imbuing party members weapons with magical abilities and such.