Right now, in the top left of my screen, there is a little bat icon with the word "Fear" next to it. What in the world does that mean?
The fear icon indicates if you are able to perform a fear take-down. When lit up you can perform a fear take-down. If not, you will need to perform a silent take-down to reactivate it.
Please also note that if you have not performed a fear take-down yet, you have to progress a little further in the story. At the start this icon comes up before the mechanic itself is enabled. You should receive the fear take-down manoeuvre with the upgraded bat suit.