I'm not a tough man. I am fairly physically fit, still going pretty well for pushing 40 with a mostly desk job, and I like to think of myself as a person with his head up and looking where he is going enough to not get caught by surprise in a bad situation.
However, should I find myself in any altercation my best plan of action is to get the hell out of dodge. I have rudimentary knife and gun handling skills at best. If i were to get into a scrap on the ground, i would probably be better off trying to crush the guy with my upper body strength with some old wrestling move i picked up in high school 20+ years ago. A man has to know his limitations.
Same thing goes for my rationale behind carrying a gun. Bad thing happens that I can't get away from...Blam, blam, blam, oh crap, oh crap, oh crap. Hopefully defensive brain kicks in quick enough to get my family away, puke, and call the cops. My knife skills are about on par with that.
Now, I carry knives and tools big enough to be formidable weapons on a daily basis. I'm very handy with a blade inasmuch as I can cut and control better than most when it comes to using them as a tool. Actually, my wife and I took a cooking class some years back and the chef teaching it actually joked and asked me if I wanted a job butterflying thin cuts of meat. Muscle memory and practice using your tools.
Today I am carrying three tools/knives on my person. A Leatherman P4 which is basically like a Wave, a Chris Reeve Inkosi, and a little Tops Ferret. Of all of them, the Ferret is probably the most viable weapon despite having a blade less than 2" long. The P4 rides in my left pocket. I keep it handy but not quick. In my right, the Inkosi and a NAA ride in a leather pouch system. The NAA part of the holster is designed to pull free with a quick tug. The Inkosi part has purposefully be left stiff so that it doesn't fall out. It takes me a solid 5 or 10 seconds seconds to get the Inkosi out and deployed. A lifetime if I were to need a knife defensively.
The Ferret is what I wear on my belt as a quick deploy package/box opening knife. It's designed to be worn as a neck knife where you pull it downward out of a kydex sheath. It's a little heavy for neck carry, but hanging it off my belt at 1 o'clock keeps it handy in a blink. It would make a terrible defensive knife due to its size, but if I had to jam the stubby blade into a knee or elbow joint, I think an attacker would feel it.
Are knives tool? Sure if you want them to be, or more likely, need them to be. Like I said, I'd be much better served booking it than fighting.