The most typical, and colorful, use of "shank" is one you omitted. "Shank" is a street and prison term for a stabbing knife, most often one fashioned crudely by the bearer. You can check this out easily. I know what I'm talking about in this instance (pardon the untrue implication that I might speak when I don't know, but I'm trying to end this sentence without a preposition...).

Working in a blue collar occupation, I've worked with several people who've been incarcerated. "Shank" is indeed a term they've used to describe an improvised weapon. Not to say that white collar types don't commit crimes, but they seem to be more concerned with dishonesty than violence.