Wind is simple enough to balance the same way everything-else kinesis/mancy can be balanced.  If the character is spending little effort to move air, then the amount of air they're moving isn't really sufficient to do much.  Air does have mass, but it's the least massive classical element out there by several orders of magnitude.  It takes a lot of g'damned air to match the inertia of something like a geokinetically-propelled boulder, or a chemically-propelled bit of metal.  Or a body.  The aerokinetimancer has to move the same weight of air as anyone else to have the same impact, and even then the force of his strikes are diffused across, generally, a huge area.  He'd need space and warning to be able to move enough air long enough to destabilize bullet flight paths, and heavier or guided projectiles would be commensurately more difficult for the aerokinetimancer to stop.

This is, of course, assuming "control of air motion", and not stuff like hardened-air shields, blades of stiffened wind, or other stuff.  At that point you're basically dealing with a funky telekinetic and need to approach both balancing and the fight completely differently, but hey.  That's where the fun part is!