Although I do not know what the clamp was used for, I can say from my experience with stamped sheet metal c-clamps that this is designed for light duty. The gap in the frame at the screw reveals a very low strength, and the handle for the screw is designed to be tightened by hand.
I believe that this clamp was designed to do more than one thing. The "wings" that are holding it upright in the photos appear to be designed to do just that. Because the hooks point up when standing up as photographed, it appears that they support something when the tool is clamped to a horizontal member. The size of the clamp implies that it is designed to mount to 2x lumber the short way.
It has the look of a took involved with wood building construction.