Adversaries can see fear. Its in your voice and demeanor. And they are not afraid of your fear. Fear is not a gift and those who think so probably have never been in mortal combat. Bad guys see it. They know it can lead to over reacting, but they also know that the fear is from a reluctance to kill them. If the reluctance is gone, the "defender" takes on an entirely difference countenance...and that scares them. The reason is that before them is not a reluctant fearful victim on the horns of indecision about taking their life. Rather they see someone who has already killed them in their mind and heart, quite dispassionately, and smiling is simply waiting for the green light to execute a plan that has already been seen to conclusion.
What your adversaries see depends on what you show them. That depends on what you feel. And that depends on how you see yourself and your role in the events. What is your self-image?