That depends on the joint. If the 'ball' had a socket drilled a decent distance into it that accepted the full diameter shaft and a bit of decent glue, it could be as strong as a solid piece. If it has a short skinny threaded rod holding the ball and haft together, it would have a short life if you hit anything with it.
The size info would be useful, if it's a three inch long item, could be a sewing bobbin.
