In my experience, the notion of silently taking out a sentry or even having to resort to drawing your knife and "fighting off the last wave" is exceedingly rare these days. Not saying it wont happen but your more likely to win the lottery. That said, toward the end of my carrier, I mounted a cold steel push dagger center of chest, accessible to either hand, on my plate carrier as a "get up off me device". Also had an Ontario RAT-3 as a stout utility knife. Always carried a rugged folder at all times and used them daily. That was the most useful knife. I've used various brands and models but can vouch for cold steel, CRKT and Benchmade among others depending on your budget. You do get what you pay for but you don't have to deny your children dental care to acquire a useful knife.
As far as "home defense", if a firearm is not an option, your probably better off with a baseball bat.
