"Decisive" means something that you can win with (nothing is absolutely guarranteed of course). Many times "decisive" will indeed be a firearm.

If you are at your bedroom doorway and your assailant is down the hall pointing HIS gun at you, "decisive" means you better have a gun too, and know how to use it. Pepper spray or a taser or a bright flashlight or a baseball bat is just not going to cut it under those circumstances.

In a different scenario "decisive" may mean something else. If the assailant is in your home, and you and your family are all locked away safe and secure in your panic room, then "decisive" might mean a phone that works when your power and phone lines have been cut (a cellphone perhaps). Call the police and let them deal with the assailant.

If you are blind, then "decisive" might mean a couple of well trained guard dogs.

But for my living situation and my family and my homes location, yes, "decisive" means firearm.

For you, in Washington, DC with the anti-firearm laws, you have to decide if your life is more important than obeying their gun laws. Sure you might end up in jail, but at least you're alive when that happens. Or you might go the guard dog route (I'm talking professionally trained guard dogs, not just buying a German Shepard and expecting it to be your savior).

Much better to keep the bad guys out of your house in the first place, but once they get inside, I want something that is as close to a "sure win" as I can get. "Might win if you're really lucky" is not good enough for me.