Ding ! Ding! Winner! I thought I might be the only one to know what that thing was, but should have known better than that! That opener style was used to open all manner of cans including oil cans, hydraulic fluids, and heavy duty food service type cans that were used for the larger (heavier) cans that the scout/SAK had trouble with. I
think it was used by someone's military for a while.
That style of can opener came out a few decades ago and never caught on. The back story is that so many folks bent the traditional scout/SAK style can opener is that they were looking for something more sturdy. I was camping a lot back thirty years ago and that design was hailed as huge improvement as it is almost impossible to bend. This was big news as almost all the scout/SAK openers on all of my fellow camper's knives were so bent they were almost useless. (Five minutes of instruction and some patience on the operator's part would have prevented 99% of that problem, but I digress...)
The blunt blade was supposed to have other utility value, defined as the owner saw fit. I hated that opener as I was used to opening my tuna cans with the other style and could do it easily and quickly. This style has faded out over the years as a lot of folks can't figure out how to use it. I used the thumbstud as a stop, and operated like this guy, but without the enthusiasm.
https://www.youtube.com/watch?v=vqAZBtVGGF8
I used a combination of punching and levering. The key to successful operation is keeping the flat side of the blade against the can's rim side. This causes the bevel to force/keep the blade against the perimeter when cutting making it a straight cut. Used the other way, the bevel pushes the blade towards the center of the lid and you lose your leverage. I know it sounds counter intuitive with the stud being on the opposite side of the flat, but the stud still works to help chew off the lid.
We found that if we sharpened it to a dull edge, that style of can opener actually worked OK. The good news is that it was indestructible. We got fast with the punch, lever, twist, remove, repeat motion, but the scout/SAK is still easier to use and will last
very well as an opener if you know how to use it.
Robert