Yeah, considering the thickness of a Jack Daniels bottle (at least if I'm recalling correctly, it was a Jack Daniels bottle), if it had been real, it probably would have killed Punk, or at least fractured his skull pretty severely, to actually break a bottle over his head.
I seem to remember TNA doing a bit a while back wherein they would "break beer bottles" over people's heads (pretty sure it was Beer Money, Inc.). The problem became that it happened every week or two and, again if I recall correctly, people stopped selling the bottle shots. This is the difference between seeing something too much and using it right. We haven't seen a bunch of broken bottles around WWE in the last decade or so, so it means something when Jericho comes out and busts a bottle of Jack over Punk's head. If it were to happen every week, it would just become another spot.
wk