Their right side is in mint condition

I was talking with someone this weekend and he said "that's a double-edged sword." I can't remember what I said that prompted that response, but I'm relatively good at putting myself in those situations. Anyway it brought up a much more important thought: Aren't most swords double-edged?

I don't see attacking your opponent from the left side only to be an effective method. I've never watched a crazy Law & Order where the person is like, "They were killed by a single-edged sword, typical. You can tell because while their left side looks terrible, their right side is in mint condition."

Like if you were going into a battle and someone said, "Here, take a sword. Do you want this one with two sharp sides or this other sword that can only cut one way?" Who would say, "You know what, I don't want to deceive my enemy. I want them to know that when swing from this side I will cut them up, but when it's the other direction it will just be more of a tap, or thwack."