My wife and I just had a rather heated argument over this one!
She says no...it did not rise to the level of brandishing. I feel that, perhaps, it did...
So after a lot of thought, I would have to say that while I don't think there was anything incorrect in the OP's response, the "better" course of action would have been to draw the weapon and keep it at the ready without brandishing, telling the perp all the "right" things while being on the phone with 911.
If the glass breaks, it's game over- and I don't think there would be much, if any, ambiguity about intent to do severe bodily harm at that point.