[K]

I think a more useful way to look to the nations is to also look at how much of a magic they get. The best types of magic require a minimum amount before they do anything good.

For example, Death 1 is enough to create a death economy. You can cast Dark Knowledge to find sites and summon Revenants. The problem is that unless claw up the hill on your tongue by Empowering one guy with the Death gems you need to slowly cast Dark Knowledge, then making a Skull Staff to summon a Death 3. Then you must live with the fact that your only good Death Mages are summoned with your short supply of Death gems.

Common Death 3 on your recruitable mages is enough to be a "Death Power." You can spam skeletons and Shadow Blasts, make a Skull Staff and summon only slightly better Death Mages, cast Terror, and with a Skull Staff make a Skull Helmet, and with either spam Drain Life. With a Helmet and a Staff you can cast almost all of the most powerful death magics.

Air on the other hand, is only actually useful if your recruitable mages are natural 4s or 5s, considering that the best battle magic is Air 6 or 7 with heavy drain, so you really want to be like an 7 or 8 with most spells. You can't even make an Air boosting item until Air 4, meaning they cost far more than any other type of magic to boost.