[It just takes a moment of carelessness, which a stabber is looking for, and the stabbing took place outside the store, so no weapon check was done.]
Not so simple. There are plenty of Arabs who look Jewish/Mizrahi, and the only way to tell then is accent and body language. Furthermore, there are plenty of Mizrahim who, due to rapes and rebellious teenage girls, have Arabian features in their makeup, and the fact that Arabs and Jews are both genetically and culturally similar, and go back a long way together. There’ve been Arab converts to Judaism, and Jewish girls abducted or seduced to living among Arabs and begetting children. Magavniks can tell an Arab a mile off, because they deal with them all day. I can’t say that I have that skill. With some it’s obvious, with others not so much.