Asymmetrical swedges on kitchen knives

A friend recently asked me to sharpen some kitchen knives. Two of them, which I believe to be 1970s-vintage at the latest:

- Case ~12cm trailing-point boning pattern
- Lifetime Cutlery (Sheffield) large carving pattern

have unsharpened swedges that are ground on the left side only.

Can anyone who was paying attention to knives back then tell me anything about these asymmetrical swedges? They are irrelevant to the sharpening process, of course, but I am curious about them from a design/marketing perspective.

What was their nominal purpose, as stated or believed at the time? I speculate that they might have been meant to increase, or give the appearance of increasing, steerability during carving.

Were they a design fad? (They give me that impression, strongly.) Something with a nominal purpose (as mentioned above, for example), the perceived value of which came and went?

Were they a visual gimmick meant to make knives look more complicated, with the implication that increased complication meant increased value? This kind of thing certainly happens now.

alkali,
Not sure. I have a few older kitchen knives and they have the same type of swedges.

Hi Alkali,

I don't know the reason for a single asymmetrical swedge, but I can offer some design "theory" that might make sense? When a blade is passing all of the way through something like cardboard the two sharp corners of the spine create friction at the trailing edge of the cut. I learned from Japanese sword design that they would create a continuous swedge on the spine of the sword, which I believe reduced friction on the blade passing through the material. I can see where a swedge might be used to reduce friction against the bone on a boning knife. Just a thought to share.

sal