Got one of these Bokers with redbone scales a while back, it really is a gem of a knife, nicely done all the way around.
To open it one handed, catch the notch on the end of the main blade on the top of your jeans pocket or your belt and pull your knife open in a steady motion. It works well with a little practice, but its not a "fast draw" kinda thing like a waved knife.
From what I can learn about the pattern, it came about after the Civil War when there were alot of one armed vets back on the farm or shop and they needed a way to be able to use a knife as they had before. This was the solution at the time, and a very simple and practical solution it was.