The definition of a double edged sword is something that could either help you or hurt you. An example of a double edged sword is an excuse that you were intoxicated when you behaved badly.

What is the purpose of a double-edged sword?

Two-edged swords have been around about as long as there have been swords. A sword whose blade is sharpened on both sides is able to penetrate and cut at every contact point and with every movement. This means that it can be thrust more quickly and deeply and can cut more easily.

When someone is a double-edged sword?

If you say that something is a double-edged sword, you mean that it has negative effects as well as positive effects. A person's looks are a double-edged sword. Sometimes it works in your favor, sometimes it works against you.