Unless you live in the rare jurisdiction that bans pepper spray and firearms but is hunky dory with you carrying some one-hand opening, locking folder with a big ol' meat-eating blade, it's hard to imagine the scenario where you're going to put it into use.
I suppose you could theoretically pull it out and wave it around as some sort of deterrent? But there's a lot of fantasy stuff out there where people are imagining squaring off with some attacker in a scenario reminiscent of West Side Story meets a "Teach Yourself Escrima at Home" DVD from Paladin Press.
The one really legitimate use for a knife is to defend against a gun grab or otherwise force an attacker off you that has grabbed you by surprise from behind.
And frankly a folding knife clipped to your strong-side pocket just isn't all that hot for that use. For starters, it assumes that your strong side arm is free and doesn't have 180 pounds of assailant wrapped around it.
Further, even if you do get the knife out of the pocket and into your hand, there's still the problem of deploying the blade. Sure, there are thumb studs and Spyder holes and flippers and assisted openers and even straight-up automatic ones with pushbutton releases. The problem with all those is that you have to get one grip on the knife to get it out of your pocket, shift your grip on the knife to get your thumb or forefinger into place to deploy the blade, and then shift your grip again to get the knife positioned in your hand to go to work with it.
And you have to perform all that hand jive while rolling around with Sumdood who's trying to yank your arm out of the socket and conk your head on the pavement. Don't drop it!
About the only folders that mostly evade this handicap are ones with the Emerson Wave or a facsimile thereof, which mostly open reliably and automatically as they're being yanked out of the pocket. Mostly. Under ideal conditions I'd say I probably get it right about 95+% of the time. Rolling around with Sumdood is pretty far from ideal conditions, though.
Hence the popularity of the small centerline fixed-blade knife. Carried in whatever way makes it best accessible to either hand...behind the belt buckle, IWB, even in some circumstances as a neck knife...the idea is that it can be reached with either hand and yanked out ready to go, already in a stabbin' grip. The purpose of these small knives isn't to square up with some other knife guy like you're Jim Bowie on a sandbar, but to do like the guy in the white shirt is doing in the above photo: Make like a monkey with a screwdriver to get the other guy to let go of your gun and/or you.
The Shivworks store has a few really excellent offerings like the classic Push Dagger or the Clinch Pick. Those are outstanding, and probably the go-to choices, but if you're on a budget, the TDI knives from Ka-Bar work great and are available from BezosMart with free Prime delivery.
(Also, get yourself to ECQC.)
