Air bending has great defensive capabilities. Water can be deflected through air current. Ice can be shattered by expanding the air trapped in the ice. Mist can be controlled as it is gaseous water. Rock can be "air blasted" into pebbles. Sand can be blown away. Metal can be rusted. Magma can be cooled. Fire can be rendered useless by removing air from surroundings. The only real threat is lightning plant and blood bending.