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.

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