The scorpion is probably (like the Roman fiagellum) a whip, the lash of which is loaded with weights and sharp points.
Related Commentaries of 1 Kings 12:11
1 Kings 12:11
11 And now whereas my father did lade you with a heavy yoke, I will add to your yoke: my father hath chastised you with whips, but I will chastise you with scorpions.