Bill Spike mystery sword? Farm implement? ID??

[Bill M]

I mentioned in an earlier thread that I am rephotographing my collection. I started numbering at 100.

I came across this mystery piece and wondered if anyone knows what it might be?

32" long, double edged and sharp. The sharpended edges begin where the blade widens out about 6" from the hilt. The edge runs along the inside edges of the curves. It is flat on one side and convex on the other. I suspect it is some kind of farm implement. Horn hilt. Well made.

The second pic shows the curved side up. The third shows the convex side.

The fourth picture shows a maker's mark, I guess, of some kind.

The seller did not know much about it, but called it a "Bill Spike." One of the reasons I got it was I like the name!