This might be a silly suggestion, but they look as though they could have had leather strips or fibre cords (string) tied around them in a sort of macrame style. If theses cords were gathered into a "handle" a few feet long, it would have made a formidible weapon, something between a mace and a bolas. The balls look to be made of some kind of granite, so they would not show significant damage if all they struck was flesh and bone.