Most of the major wrench makers supplied 'specials', they were nothing more than non-standard combinations of sizes in most cases. The wrench was probably intended for a machine that only needed those two sizes. Since other machines might also need a wrench with only those two sizes, the wrench makers could make out by offering the 'special' combinations (sans custom lettering) somewhat cheaper than a full contract wrench. Which means your wrench might fit multiple things, particularly as 1/4x3/16 isn't all that 'special'....
I suspect the odd head proportions are more from sticking a 1/4 head blank on a handle originally intended for a smaller head than any indication it was intended for high torque, also, note that the head on the special you have is less circular than the wrench you are comparing it to, I suspect it is a later design....
