That being said, shooting one blank would tell the BG that your am sucks
If someone is coming at you and you feel that you need to pull the weapon, pull it. Deciding to shoot is something that you need to decide based on the circumstances. Maybe "brandishing" the weapon will make the BG think twice and maybe lead poisoning is the only thing that will work on him. Have your game plan put together before you get into one of those circumstances. I went through an "evolution" of carry myself and you have to look at every situation differently and be ready for it.