Shockwave can always travel through air:|. [Since when do shock waves travel through the air? And all they managed to do was break the tip of his sword, and that's only because Obito stopped his attack midway.
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]. PS sword slashed through Obito's sword as well as Obito at the same time. And no where it shows Obito stopped his attack.You can see in the left bottom panel, that the sword didn't touch any of the pillars [Those aren't shockwaves. He simply destroyed the pillars of the building with a melee attack. The building collapsed as a result.
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]. Further more, anime shows it was shockwaves.