What a weakling the lover of the husband's wife was

Not only does he let the husband strike the wife to kill her when he practically telephones in what he's going to do a few seconds before, and is in grabbing distance of the weapon, but for someone who is also obviously more athletic and more in shape, lets the husband get the better of him to kill him as well. It's not as if he had a gun or anything, it was just a pair of scissors wasn't it?

Also, did it kind of bother anyone else that Burgess didn't kill himself by going for a head shot? It seemed like shooting himself in the chest was a needlessly risky way of ending his life, in that it's probably not as guaranteed to be as fatal as a head shot. Obviously it looks better for the film though because then they can have the shot of Burgess and Anderton up close, not knowing who's been shot initially after the gun goes off.