Double Ball Flail

[PacificSkyGames]

The "Double Ball Flail" was originally an agricultural instrument used for threshing grain. However, when impromptu use showed how effective it was, it was quickly adopted as a weapon of war. Soon the standard flail was replaced with flails designed specifically for warfare. The spiked flail was quite popular, but soon someone got the idea of using two smaller spiked balls with two chains, to increase its effectiveness.

Morning Star: The morning star is a medieval weapon that consists of a spiked ball on the end of a chain attached to a pole. It is a derivative of the mace.
A combatant would swing the ball on the pole around his head and attempt to strike his opponent with it, often with deadly force.
Sometimes, instead of one large spiked ball, the pole was attached with 3 spiked metal balls connected in chains. This modification is called "flail".

This is all I have found so far. I will get back to you with more accurate sources and the dates of use.