It needn’t be the spiked ball on the end of a chain which you see in movies. Those seem to be highly dangerous for the user. Those did exist but the use wasn’t widespread. I’m talking about a spiked club at the end of a staff. It would be effective against those weilding a shield as it could reach over the top of one and hit an opponent’s head.
I’m finding these medieval weapon videos interesting because I’m customising action figures and and trying to work on melee weapons.