Spear with cast iron ball end: Ideas please

[Atlantia]

Trying to help an offline friend Identify an unusual acquisition.
Sorry, no pictures as I wasn't expecting to see it when I went to see him and he's quite a way from here so I can't pop back with a camera.

A 'spear' with a hand forged slightly crude but very effective, heavy guage socketed spear head, with a single hole right through for attachment.
A thick (like a thick broom handle) shaft with a cast iron ball of 'cannon ball' size at the other end.
The ball has a hole right through it and an integral 'collar' where the shaft enters. There is a visible casing seam right around it.
Lots of dark old patina on the metalwork.

Here is my usual scribble to give you some idea.
The overall length is 4'3". It's very heavy and the POB is a handhold in front of the ball.