Practice makes perfect in the fine art of being menacing. Gifted intimidators can largely get whatever they want without actually resorting to violence, while less gifted ones wind up being victims of said violence. One of the valid skills that can be used with the 'convince' command.
0: If you're bigger and scarier some people might buy it. If you're smaller and not scarier they might humor the lunatic screaming at them.
1: You have a glare. It's a pretty good glare!
2: Your glowering is A+.
3: Your ability to convey potential, impending violence could now be taught at the college level.
4: Everyone is scared of you but never seems to notice that you don't actually need to hurt people.
5: It honestly doesn't matter how dangerous you really are, everyone just takes you seriously.
6: Even when they are far, far, far scarier.