I thought that giving a warning of being armed or flashing the holstered pistol would be considered brandishing. My understanding has been that you can't give them a clue you have a pistol until it's time to draw and fire.
Now that gets back into the debate of if you pull it you must use it. Because if I pull the weapon and the would be aggressor says oh shi* and turns tail and runs I'm not shooting him in the back.
If I have the distance between say them and myself or something between them and I and the situation is appropriate say they are walking hastily towards me with a knife or baseball bat saying they are gonna bash my skull in and verbal warnings don't work next step is a visual warning whether you unholster your weapon or expose it and put your hand on it.
Now if brandishing the weapon ends the conflict I would still call and make a report with any and all information.