He can solidify air with magic. I assume that he cannot do this with other elements like water. I wonder how far away he can make a piece of solid air?
Abilities like this one can be very deadly If used correctly. For instance, he could create a blockage of solid air inside the lungs of his opponent. They would be completely unable to breathe, and would succumb within minutes. If he had the ability to create air instead of using air that surrounds him, he could create an embolism that would block blood circulation into the brain. His victim would collapse as if they had just had a stroke.
I have only seen this type of application described in a particular Naruto fanfiction, where a variant on the shadow clone technique was used to place a steel knife inside the brain of someone, killing them instantly.