No one has mentioned it per se, but IB gets it: Demeanor is a weapon all by itself. It doesn't help with a blitz attack by a drug-addled desperado, but projecting confidence despite circumstances and surroundings can change "inclined to attack and rob" to "disinclined to attack and rob."
Here's the mantra, with apologies to God Almighty if there is one and King David in any event: "Yea though I walk through the valley of the shadow of death, I will fear no evil, for I am the baddest motherfucker in the valley." That's from the movie "Jarhead," but I'm pretty sure I knew it from somewhere long before the movie.
It doesn't work in a "toughest guy" confrontation. You know, someone who is going up against everyone to prove he's better. That guy seeks out the best. In that case, well, just shoot him.
