I think what Bobboau means is that when you play the ani frame by frame, you see that the rays eminating from the blastcenter, are completely static, even though the blurriness and such...
since you are hitting an energy field (locally destabilising it), these rays shouldn't be static, they should be moving a bit, somewhat like a faint electrical arc, moving over a conductive surface.
To get an idea think of an effect simmilar to those glass ball things where you can put your hand on the glass and the charge moves where you touch the glass...(haven't got the foggiest what these are called), only less strong since the discharge is on an energy surface.
And perhaps even, especially since you are hitting a charged surface, make the blurriness less appearant. (an energy discharge effect should be more welldefined AAR of polarity effects)
How it should fade? well, again, it being an energy charge, it should probably fade more like it is emenating less light intensity instead of spreading out like an oil spot....shockwavey effects would not be that visible I think...