What does Judges 9:53 mean?
The people of Thebez are trapped inside the city's fortress tower, a building likely made of stone. Abimelech and his men have taken the rest of the city, but they will have to defeat the tower to overtake the town (Judges 9:50–52). The tactic Abimelech chooses here is to burn down the tower's door, which would have been made of wood. Perhaps he hopes to then gain access to the tower and fight his way to the top with his men and kill the city's population. This easier said than done, since the people on the roof of the tower can fire arrows and throw objects at those who get close.In this era, milling grain involved the use of two stones. These were often made from dense, heavy basalt rock. The grain would be placed on the lower millstone, which was stationary and weighed as much as a person. The upper millstone was usually shaped like a wheel about 12 inches, or 30 centimeters, wide. These could vary in weight, but this one was probably about 25 pounds, or 11 kilograms.
It's possible the people of Thebez were throwing random objects from the tower anytime an enemy came within range. A woman of Thebez either fled with her upper millstone, or more likely, found one there on the roof. Scripture does not say whether she was specifically aiming for Abimelech. Apparently, it was noticeably clear that she was the one who threw the stone. Perhaps she shouted something as she threw, or Abimelech had seen her looking over the edge.
In any case, this woman delivered the deciding blow of the battle. Her position on the roof probably meant she was a few stories above the ground—and she drops a solid stone wheel right onto Abimelech's head. The blow is not immediately fatal, but his skull is crushed. He knows he's going to die, and his dreadful vanity can't handle the idea that a woman delivered the deadly strike (Judges 4:21–23). He asks to be put down by a man (Judges 9:54), though this won't change anything. King David will later refer to this moment (2 Samuel 11:21), specifically noting that the woman was the one who struck the crucial blow.