I'm not talking about brandishing or open carry. The most common deterrent I've seen from the the (literally) thousands of violent encounters I've seen on "Active Self Protection" is that criminals start running and scrambling when the victim counter ambushes with their _concealed_ gun, whether they even put a shot on target. The victim should put a shot on center mass as that puts the criminal in "FIBS" mode, "Fudge I've Been Shot", and their shooting accuracy plummets drastically. To the extent that a victim can close the distance and counter ambush with a knife, that could be effective. Guns are a range weapon which is extremely useful in a gun fight. Brandishing a knife is likely to get you shot if you aren't ready to immediately use it.