What does Judges 3:16 mean?

God has raised up a new "judge," a national deliverer, to save His people Israel from their Moabite oppressors. Ehud has been selected to deliver Israel's tribute to the king of Moab, Eglon, at the king's palace in Jericho. He sees an opportunity to save Israel by assassinating the enemy king.

To prepare for the moment when he might be alone with the king, Ehud makes for himself a two-edged sword. This verse describes a weapon only one cubit long. This is typically measured as the distance from a man's elbow to the tip of his middle finger. This sword is therefore more of a dagger, and probably designed as a piercing weapon. Medieval warriors might have named Ehud's weapon a rondel; modern persons might describe it as an oversized ice pick.

The fact that Ehud made the weapon himself also suggests a compact, thin, stabbing weapon. The "shank" style of weapon is common in situations where resources or tools are limited; Ehud was not likely a metalworker. This blade is short enough to be strapped to Ehud's thigh under his clothes, without being noticed by anyone. Because Ehud is unusually capable with his left hand (Judges 3:15) he can secure the weapon in an unexpected place: his right thigh, deploying it with his left hand, making the attack all the more unexpected.