It's an old french saying, in french society yougsters were given a knife around the age of 15, even among the poorest families.
So, even if you were broke and had nothing, you still had a dick and knife.
By derivation, used to describe anybody trying to perform an action empty-handed despite some equipement was required.

When someone thinks they are the main character of their life. Usually comes with a side of individuality complex, quirky style and a self centered point of view.