Achilles

This poor guy was armored big time, possibly thinking he was invincible. And guess what? Well, you know what. He got killed. Shot with an arrow in his achilles heel. Therefore the expression in case you didn't know where it came from.

So, everybody has at least one weakness. News? Not really. And I have many :)...have just chosen not to share them. That's the privilege of my friends to discover :)

PS. Got to think about it since flatmate has injured his achilles.

Again, for the serious people:
http://www.pantheon.org/articles/a/achilles.html