In a setting where the world consists of islands drifting in an endless sky. The traditional European/Hermetic 4 way elemental split seems a bit unbalanced...fire and water, I can see the opposition and balance; but earth and air seems heavily dominated by the latter, when earth composes the tiny chunks of floating matter and air consists of almost everything else in existence.
Maybe an eastern elemental split is better...earth, wood, metal, fire, water. We still get the relatively balanced fire and water. We now get wood (the essence of life and vitality) opposing metal (which can embody machines and sometimes unnatural things). They each centre around earth, like the floating rock platforms on which the people of this setting live. Air is not represented in this cosmology because it is an intrinsic part of everything...specific abilities become focused on those outside elements, while the actual power level of the individual is determined by the central element (the earth).