Has to be the tinest one that I can remember finding! Must have been for a particular SMALL application!!
Magneto / ignition wrench
I always wonder how many of those went down the carb into the motor amid a chorus of swearing and cursing...
Most tiny stamped wrenches with numbers starting with 'E' are for magneto or point adjustment (E-Electrical) , almost everybody seems to had the same idea about numbering ....