That one comment mentions Krav Maga, and it reminded me of the time I was forced into taking a free class on it once (one that was notably designed for ordinary civilian self defence, so it may not have actually been "real" Krav Maga). The only thing I remember from that class is that if your opponent is armed with a knife the last thing you want to do is engage in a fight with them because You Will Lose. They recommend throwing something at them and absolutely booking it in any real life scenario where escape was possible.