The false edge reduces the width/mass of the spine allowing for less resistance when stabbing your assailant as well as less drag when removing the blade.
Also, in regard to a "chute" knife, which was used to cut away tangled parachute lines, if the false edge was NOT false, and actually sharpened, as you were plummeting to your death in a tangled parachute, the trooper could slash away at the tangled lines and cut with the knife in any direction! Thus, getting rid of the tangled chute and then opening the reserve chute.
The distal taper reduces forward mass of the blade and places more weight in the center of the knife where it belongs.
Ever notice that many leaf springs are tapered in width and thickness from the center to the ends?
As more weight/stress is placed upon the spring at the shackles, it transfers to the heavier mass of the spring. Thus, there is no "weak" spot in a tapered piece of steel.
If it was all the same thickness and width, stress would "find" the weakest link in that chain and break the blade.
It's a physics thang.