Nelson Shin's story about suggesting the sound does seem embellished. AFAIK Ben Burtt came up with that sound all his own
Also I have read elsewhere that Barry Nolan at Van der Veer Photo Effects did the glows. But maybe that was only some scenes?
I forget, was that glow on the ceiling beam in the original shot there on the whole shot, or was it an "environmental" glow that was double exposed in only during that impact animation?