Sword Trail Distortion

Has anyone tried this before?
There are several games that i have played before where weapon trails distort air as the weapons slashes.

Example seen in Dragon Nest:
Sword Trail

It would seem like a normal map might be used?

 

In Star Wars: Jedi Outcast they animate a mesh to lag slightly behind the rest of the lightsaber blade. It works, even on older platforms (This is a pretty old game, after all)
It easier to see when you show the wireframe.

In JKO they simply use an alpha blended texture. It seems that in Dragon Nest they refract everything that has already been rendered, probably indeed using a normal map to determine the 'shape' of the refraction (to offset texture sampling of the grabpass).