Mystery Hand Saw Rescue and Restoration

I have never seen a saw quite like this. Please let me know in the comments if you know what it is or have seen one before. It was in really rough shape and I decided to try to save it. The odd looking little metal piece shown at 5:40 was embedded in the handle slot. I figured someone had put it there to help stabilize the blade. I just removed it and replaced it with the steel insert shown in the video.