Zig Zagged: Hiro is a knight, who learns one healing spell to help a friend in a moment of need, just in case Marcy is taken out, but then never needs to use it. Then he sees how useful Dennis' combat magic is, and decides to take a level in lightning. That works incredibly well, until he meets an enemy immune to it. Then, he trusty old sword saves the day.
Averted: The rules of the world make it impossible to be powerful with both magic and swordfighting, so Hiro has to pick one or the other.
Enforced: I've got a loner hero, and I'm a swordfighting expert, but he needs to have magic, too. I know: I'll make him a Magic Knight.
Lampshaded: "Before long, I'll have you casting Fireball with the best of us. And then: you will be a Magic Knight."
Defied: Hiro doesn't learn any magic, so that he can become a highly skilled swordfighter. Meanwhile, Emperor Evulz has undead minions fight for him, so he doesn't have to worry about this "swordfighting" business and can concentrate on taking over the world.
Reconstructed: After his mentors bring Hiro Back from the Dead, they make sure to not overwork him so badly again, and find ways to combine classes. He ends up able to fight 3/4 as well as a full knight, and use magic 3/4 as well as a full mage. Net result: 3/2 as much power as anyone else.