✅ SOLVED 15th Cavalry Distinctive Unit Insignia, but what is it?

[batcap]

This was not dug, but found in a basement. It weighs a little over a pound and it feels like it could stop a bullet.
What is it? Flag pole top? Hood ornament? BTW for those like me that are French impaired: "All for one, one for all"

 

[NOLA_Ken]

I would think flagpole topper with the threaded base like that