Ah. He ONLY did this for me right before he switches sides with you for the 1st time. He would go BIG laser, then jump. But if I caught the whole thing, then hit him with it, he would keep on shooting. Only when I didn't return it would he move on. You are right, normally when he does this during the fight he will just move on with the missles. I actually don't recall very well if anything after that was shorter. If I can find the time I'll see about making a movie or something, but don't count on it!
oo! I found a movie!
http://www.youtube.com/watch?v=cwgqjI_ZhM0 The player isn't exactly the best and it doesn't show what I'm talking about but it will at least help you understand the moment I'm talking about. At about 1:05, the player hits him with a missle, and the beam is firing. It's this moment right here that if you catch the beam and then hit him with it, he'll fire it again. Catch again, hit again. Repeat till tired.