God continues speaking of the armies of Egypt and Babylon as if the armies were the arms of their kings. He also speaks of making the army of Babylon strong to attack others as if he had a sword and put it in the Babylonian king's hand. (See: [[rc://en/ta/man/translate/figs-parables]])
Here "arms" are a metonym for the army. Alternate translation: "I will make the army of the king of Babylon strong" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Here "Pharaoh's arms" is a metonym for his army, and "will fall" represents being weak. Alternate translation: "but Pharaoh's army will be unable to defeat enemies" (See: [[rc://en/ta/man/translate/figs-metonymy]])