When the king of Babylon stood at the crossroads and cast lots to decide whether to attack Jerusalem or Ammon, the omens directed him toward Jerusalem. Consequently, the Ammonites, who had previously joined Judah in rebelling against Babylon, were temporarily spared. Rather than recognizing the precariousness of their own situation, they rejoiced at the downfall of the Israelites. The prophetic focus now shifts to Ammon, shattering their illusion of safety and declaring that the very weapon that devastated Judah will soon turn against them.
The prophecy addresses the Ammonites and their profound disgrace. The primary approach among commentators is that this disgrace refers to the insults and mockery they hurled at the Israelites upon seeing Nebuchadnezzar bypass Ammon for Jerusalem. They celebrated the destruction of the land, boasting that their luck and their idols had triumphed over God and His people [רש״י]. Compounding this malicious joy, the Ammonite king committed a further atrocity by sending an assassin to murder Gedaliah the son of Ahikam, attempting to wipe out the last surviving remnant of Israelites in the land [מלבי״ם]. Alternatively, the disgrace mentioned is understood as a direct reference to the Ammonite idol itself [ביאור שטיינזלץ].
To illustrate the impending danger, the arrival of a sword is declared repeatedly to emphasize the intensity of the threat [מצודת דוד]. The weapon is already unsheathed and fully drawn [מצודת ציון, מלבי״ם]. The message to the Ammonites is clear: they must not mistakenly believe they have escaped. The blade drawn to destroy Jerusalem remains unsheathed and will not be put away until it strikes them as well, whether by the hand of the Babylonian king or later by other empires such as Media and Persia [רד״ק, מלבי״ם, אברבנאל]. Another perspective suggests that rather than referring to the unsheathing, the description indicates a blade that is thoroughly polished and sharpened [רד״ק].
Ready for slaughter, the weapon is honed for a specific capacity. The primary approach among commentators is that it has been prepared and sharpened to withstand the immense burden of massive killing, enduring the physical wear of the slaughter and claiming many casualties without sustaining damage [רש״י, רד״ק, מצודת דוד]. A different interpretation focuses on the grip, suggesting the hilt is polished so the wielder can hold it firmly and steadily [מלבי״ם]. A unique perspective proposes that the blade is meant to be fed, with the warrior feeding the metal the flesh of the slain [רד״ק בשם אביו], though some commentators reject this interpretation [אברבנאל].
Finally, the blade is polished to achieve a brilliant, glowing flash. This intense shine is intended to strike terror and dread into the hearts of any nation that beholds it [רד״ק, מצודת דוד]. The gleam of the metal is so bright and powerful that its fiery appearance will not darken or fade, even when it is deeply plunged into masses of casualties [רש״י].