That was, in fact, not my source for ideas. It wasn't "how to make this lethal," it was "let's say we had an elemental that didn't bring material with it." My first idea was the Earth Elemental that, instead of dragging a bunch of rocks along, moves like a wave - none of the stuff actually moves. Then I decided to expand it. Water worked the same way, again with only limited ability to bring material with it, and added drowning because it's not an idiot, and ice equipment because, hey, water is three-state and two of them fit here. Fire was the same - if it can't bring material it needs existing fire - plus blasting because it's not solid.

The problem with going the same way for air is that that's been done - the standard air elemental turns into a tornado, and Invisible Stalkers handle the you-don't-notice-it.

What was left as unexplored space? Even more than earth, air is everywhere, and its also the least dangerous, so I decided on a primarily non-combat creature based on presence.

Regarding specific suggestions:
Vacuum doesn't work because the whole thing is that they are air, not the lack of air. The Kindlewraith can't go out, the Aquiform can't give you a bubble to breathe, and the Mounder can't give you a comfortably large cave.

Poison might fit a corruption, like an Acid-based Water elemental, but... When I think poison, I think liquids and solids long before gases.

And I've got control of windspeed in the current scratchnotes for the Eye, as well as fine movement.

Thanks, though.