The gathering of many nations to besiege Jerusalem might appear as a terrifying threat, but it is actually the setup for their ultimate downfall. They are brought together much like bundles of grain collected on a threshing floor, perfectly positioned for the harvest. The prophecy calls out to the people of Jerusalem, who have been weakened by the long years of exile, commanding them to rise up and strike down their enemies [מצודת דוד]. This dramatic confrontation is understood to take place during the future, climactic war of Gog and Magog [מלבי״ם].
The imagery shifts to a powerful agricultural metaphor of an animal threshing grain to separate the worthless chaff from the valuable wheat. God commands the people to begin this threshing process, and to make it possible, He provides them with entirely renewed strength. They are given iron horns to fight, gore, and bring down the massive enemy hordes. Their hooves are transformed into copper, acting as heavy metal shoes to trample and crush the opposition. This violent threshing process has a clear purpose. It is meant to sift through the nations, destroying the wicked until only pure, clean flour remains [מלבי״ם]. As a result, the opposing armies will be completely crushed into fine dust.
Following the great victory, the focus turns to the enormous spoils left behind. Speaking on behalf of the people, the prophet declares that they will dedicate all the precious wealth of their defeated enemies to God [מצודת דוד]. It is also suggested that the spoils will be divided, with a portion kept by Israel and the rest consecrated to God [רד״ק]. When describing this treasure, the commentators discuss two distinct terms used for the enemy's assets. The primary approach among commentators is that these terms are simply poetic repetition, both referring generally to the money, precious items, and property of the nations [אבן עזרא, מצודות]. However, others draw a sharp distinction between the two concepts. The first term refers specifically to wealth the nations gathered unjustly through the robbery and oppression of Israel. Because Israel is holy to God, this stolen money retains its holy status and must be returned and dedicated to Him. The second term refers to the nations' own original assets and power, which were not stolen. Yet, even this legitimate wealth will ultimately be handed over to God, recognizing His position as the Master of the entire earth [רש״י, מלבי״ם].