I've had this peculiar vise for ages, and thought it might be a saw vise designed for sharpening small handsaws. The ad below, reproduced in a history book, enlightened me. I presume that the vise was used to hold adjacent sections of the leather harness in place before sewing them together.
Reader's Digest Association (Canada) Ltd., In Search of Canada. Montreal, 1971.
Somewhere or the other, I also picked up a shoemaker's hammer:
Maybe I can embark on a second career in boot repair, but I need one more tool and it will be my last stand.