Masters of the Skies
Air Mages are absolute masters of flight, outclassing even the winged races in some cases. Whereas most figures in flight would be forced to land in the face of rain, sleet or snow, an Air Mage can brave such conditions with ease, even able to fly in and out of dark and dangerous thunderstorms while coming out unscathed. Still, even they have limitations, more than a few having perished hot-shotting around Tornadoes or seeing if they could reach the eye of an approaching hurricane. If the air mage is not of a naturally flying race, the Fly spell is still required.
Yet unless I'm reading it wrong, since they need the fly spell, if fighting in the air they are still subject to the -10 STA per turn penalty if they're not of a naturally flying race, whereas these only take a -1 penalty. There's nothing in this that suggests anything about "outclassing even the winged races".
Air mages are masters of the air. It is the essence of who they are. They have the power to direct the wind, summon cyclones or thunderstorms, or even drain the very molecules in your lungs. They can in fact (those of Unigo at least) become air! Yet when it comes to actually fighting in the air they're no better than anyone else, really.
It seems reasonable that they should be at least as nimble in the air as a torian or a chirot, I think, even if they still need to learn to use magic to fly, and stamina drains should reflect this.