To follow up, I have discovered, I believe why my Pointcut Pruner is rather rare.
I adjusted the fit of the blades and sharpened it, then gave it a try. It worked just fine, but it is only 20" long, is much heavier than other pruners that would have wooden handles and a much simpler blade arrangement, and, of course, it cost $5.00 in the depths of the Great Depression. Likely it was not a big seller.
I suppose HKPorter assumed that a pruner should have a design similar to their bolt cutters.
Not so.