Here is my thoughts, and I am sure someone wont like them.
You have a right to be safe and do your job. I carry things like pens that can be used as improvised weapons in a pinch. Here is an example https://www.amazon.com/gp/product/B07N67VB8H
If someone comes at my in a violent way and I don't have an easy escape route, game on. Remember, anywhere you are conducting post office business is under federal jurisdiction and that makes their threats and actions federal crimes. Always, always call the cops after an incident and tell them you are a post office worker and were threatened. Press charges and notify supervision. You are also allowed to skip a delivery anytime you feel there is a risk to your safety. Dogs, obstacles, etc. Use this when appropriate but not as an excuse to be a dirt bag.
I also don't carry the dog spray (due to the inherent safety issue it causes by having ZERO safety on the spray actuator. Instead I carry POM. It has less potential for back blast due to wind and is safe to carry. Works on both 2 legged and 4 legged dogs.
Top: Blocking Wand ( http://merchandisingtools.com/blockingwand.html ) We got ours before they are redesign. I am enough of a grocery geek that I'm considering picking up a 3 pack of the new ones.
Left to right:
Out of stock Tag: can never have enough of these, I will scrounge and dig to find more fairly often
Tactical pen: I was sick of losing pens, so this big guy stays in my pocket, and not my apron.
https://www.amazon.com/KEPEAK-Military-Tactical-Professional-Emergency/dp/B07N67VB8H/
Standard and big Sharpies
Folding scissors: Basic and cheap, you can see it waring down to the copper, not the same but similar in link.
https://www.amazon.com/Folding-Scissors-Pack-of-2/dp/B071SBPHVQ/
Elmers Glue stick: So many loose labels are simply fixed with this.
Pacific Handy Cutters: https://www.amazon.com/dp/B003FJ9U7W/
Pacific Handy Cutter Leather Sheath (If you carry a box cutter, this guy is a must!) https://www.amazon.com/gp/product/B015MG0J20/
Standard Notepad: My short hand is big and we go through a lot of those. This is a new one. I usually keep a rubberband around it to keep the worn pages from flapping everywhere.