The Shield of Air is a weave in the One Power; it is a specific kind of the Hardened Air weave, and it is used as protection against enemy attacks.
The shield can take any shape and dimension, from a simple wall to a great dome over a large portion of the ground. Depending on its hardness it can repel totally a projectile from an adversary or more simply slow the run of some arrows, to make them drop on the ground before they can touch their objective harmfully.