If you wonder why the inner part of the Ranger blade is not sharpened? The inner part is not sharp because it functions like a stopper for the blade. This part stops against the notch on the spring to protect
the edge from impact with the spring. It is a stopper function. When the blade is closed the lock-release has no function but it can move freely without damage from the edge. The notch functions as a rest for the blade.
It is also normal on SAKs to use notches on a spring to function as stabilization. By this is mean from twisting motions and more. I would believe this notch serves different functions for the assembly and construction of the knife.