I can't believe I'm saying this, but, I'd like to be serious for a moment. My Mum's brother spent almost 2 years in Burma side by side with the most feared knife fighting troops in the world....three guesses who they are. He once asked if they ever threw their knives, and the answer went something like this: " A Gurkha throws his knife, maybe one dead Japanese. A Gurkha keeps his knife, many dead Japanese. A Gurkha would rather cut off a hand and throw it, than throw his knife." I'm paraphrasing, of course, but the gist is there. On another note, there are maybe a couple of hundred people on this planet who could throw a knife hard enough and accurately enough to kill someone, first time, every time. Also, if you carry a big, badassed knife, people expect you to be able to use it well.
edited to correct typo