The Indian club bell has been in the US since the mid 1800's. They are often surprisingly light, compared to barbells and such. Between that, and the fact that I can see the chalk marks left on it from it's previous owner, I am certain that is what it is.

Try doing some exercises with it, and see how well it works the wrist and forearms. All the basci/classic clubbell exercises are on youtube.

I think you will be surprised at how well they work.