Your greatest weapon is good situational awareness. Don't let yourself be an easy target. Make a show of assessing your environment, and avoid isolated areas when possible. Talk to people, try to generate attention. I like to keep my hands free, so I carry my essentials in a messenger bag or backpack. It allows me to interact more with the environment, not show off my purchases, and it can be used as weapon if I'm truly desperate. Don't be a willing victim. Alot of the old clichés ring true, if you have to get physical, get dirty, and fast, there are no points for gallantry. Bite, scratch, use your keys, and if you're big use your weight. I'm a decent sized guy, so the few times I've had to defend myself, I dash in, grab something and hold on while I punch, kick, or grapple. You might get hurt too, but any damage you can cause can be used to identify your attacker later if necessary. I got attacked a couple of years ago by an opportunistic teen, after the flurry was over, I had him grounded and twisting his arm. When policed arrived on scene, we were both bleeding. After we got cuffed, questioned and our injuries attended to, the officer gave me a stern talking to about endangering myself. He also told the kid that he was an idiot for attacking me, as I had forty pounds on him. When it went to court the kid had a broken nose, dislocated shoulder, a spiral fracture in his forearm, a few cracked ribs, and a severely bruised ego. I had some scalp bruising from having my hair pulled and headbutting him, as well as some scratches from rolling around. He got off for time served while waiting for trial, and community service.

Travel with purpose, and stay alert.

There are some self defence programs that are designed specifically for the blind. I'm not sure how effective they are, though.

https://www.1touchproject.com/

https://www.visionaware.org/info/emotional-support/dealing-with-crime-or-domestic-violence-as-a-person-with-a-disability/sightless-self-defense/125

As for a stun gun, it would depend on your local laws. In Canada, that product is illegal. Also, the zap cane is not as effective as people imagine.

EDIT: Here is a video of some reporters trying it out. https://www.youtube.com/watch?v=cB5w7RsiTYQ Even two stun to his chest, he was still up and talking.

Stun guns have worked for me quite effectively.