'Flail' in the Bible

And Gideon said, "Well then, when the LORD has given Zebah and Zalmun'na into my hand, I will flail your flesh with the thorns of the wilderness and with briers."

Certainly caraway seed is not threshed with a sledge, nor is the wheel of a cart rolled over cumin seed. Certainly caraway seed is beaten with a stick, and cumin seed with a flail.