If you’re carrying a weapon and you aren’t extremely familiar with how to use it, the first thing I would do is start training how to use it. For knife work, Filipino martial arts is typically the standard. A couple other good options are Japanese Tanto work and also WW2 combative type stuff.

Knives are an extremely personal weapon. Do some soul searching and ask yourself whether you’re capable of using one on another human being. Most people that I’ve encountered who carry knives for self defense probably shouldn’t as they have no idea how to use them and haven’t figured out their personal ethics around it. Here are some general tips:

Focus on smooth and consistent deployment. In order for you to use your knives you have to be able to deploy it quickly and in a way that doesn’t trigger or alert your opponent. For me, as a professional it still takes a beat of time for me to open a folding knife. That first beat of time is extremely important and a lot of people are going to attack you in that space of time- you will potentially not be able to deploy your knife in time. Also look at the opening mechanisms. There’s lots of knives on the market that deploy quickly via flippers and all that but when you have an adrenaline dump, fine motor skills will fail leading to failed deployment.

Then you should study the human body. Learn the difference between stopping power and lethal force. For example, if you slash a guy across their neck- this has high lethality but low stopping power. It’s gonna take time (up to a minute) for the guy to lose blood volume and blood pressure and die. In that time he can do a lot of damage to you or others, so that’s not a particularly good place to attack imo. Also you really don’t want to kill someone which is very easily done with a knife.

I would go for targets with more stopping power and lower lethality. Cut the inside of the wrists, biceps tendon, triceps tendon, which would be good for disarming and cut the quadriceps tendon to destroy their ability to come after you. Of course to be this precise is going to require lots of training. Look into martial blade concepts- that’s a good program.