It’s just a gas lighter. It’s unlikely it will set someone on fire. They would have to be wearing something extremely flammable. To actually set someone on fire you need some agent that will stick to them like gasoline. This will most probably just burn someone’s hair and it’s a good thing. Using actual flamethrower as a self defense weapon would be insane. The chances of hurting yourself or setting whole building on fire would be really big. You could just a well carry a bottle of acid with you.