My guess is an early life saving device for Lumber Jacks working more than 10 feet off the ground,, probably known back then as a Sky Hook. On the fast track down after the Jack mis-stepped one of his tree spurs he would simply unhook this from its scabbard found on his belt and toss, like an anchor, into the branches going by at warp speed. Of course,, most of those great American hero's were intelligent enough to attach a rope into that hoop above the hooking device before tossing it.. Noticing that your fathers specimen does not have said rope Orlin,, I am guessing that this one in particular was owned by a less intelligent Lumber Jack and that is also why your Dads Sky Hook is still in such very good condition. Probably spent its life stuck in the branches of 70 foot Douglas Fir tree while protected by the trees canopy above.