Everyone has different ideas about what they consider self defense tools and what they trust. We all have different hand sizes and different ways of carrying and what and how we carry. That's what is great about Spyderco and all of the choices that they have.
I carry a gun (Glock 26) all of the time except at my office where it isn't allowed and at my sons school. I also carry a Glock 19 and Beretta 92 along with the G26 at times. I may also throw in an LCP or this and that, but the G26 is always there. I don't shop at places that don't allow carry. I like having a knife as well though, even if I have a gun. I'll never pull a gun unless I plan on using it and hope that that never happens. THe same for the knife, but a knife might be a step before the gun and might scare someone off. Or if they grab my wife's purse, I could cut at the threats arm to release.
I constantly go through scenerios in my mind to be mentally ready if need be. Stay safe.