He seemed pretty sober in that scene. During the occupation arc he just liked his tipple after duty hours. It was only after Federation forces took the station back and he got stuck with Weyoun, realizing more and more how powerless he really was, that he started knocking the stuff back by the bucketful and getting drunk on duty.
Not only wasn't he drunk during their confrontation, but they were squaring off challenging each other, so he was expecting
her to attack him. So it's not like he was unprepared in any way.