Take a look at the Spyderco Civilian. It's designed so that ONLY slashing cuts are possible. It was designed for a federal LEA, as a last-ditch, get me outta' here thing.
I was taught that a folding knife would cut you, a hunting knife would cut you to the bone, and a fighting knife would cut through the bone. That came from the observations of a WWI vet many years ago. It's a bit impractical to go about with a 7-10" heavy-bladed knife in today's world. In fact, in many areas, the open display of a sheath knife will draw unwanted attention faster than a peek at a holstered pistol will.
A skilled person can make a 3" blade folder of good quality a substantial weapon. However, under normal circumstances, a gun is going to be a more lethal weapon.