People can be compelled by fear to escalate a verbal argument into a fight. Seen it happen on more than one occasion.
Arguably, fear is a leading cause of such escalation. The person who feels they are losing the verbal argument escalates to avoid losing, to avoid being seen as weak, to avoid losing face, etc.
Out on the internet, you can find lots of videos in which some punk is harassing an experienced martial artist, an older boxer, a war veteran, someone like that. And the person being harassed is failing to respond with deference, fear, or whatever emotion the punk was seeking to inspire. Rather than seeing this as a warning (If he isn't afraid of you, what does he know that you don't?), the punk continues to escalate until he finally does something that demands a physical response. Lesson in the importance of respecting one's elders ensues.
Point being that the ability to *not* be afraid is, in and of itself, an extremely powerful weapon.