Prophetic visions often utilize vivid imagery to convey the magnitude of historical events. The striking metaphor of shaving hair is used to depict military defeat, widespread destruction, and deep humiliation. The act of shaving symbolizes slaughter, while the razor itself serves as a metaphor for a destructive sword [רש״י, מצודת דוד]. Other commentators view the razor as a severe plague or an angel of God that struck the Assyrian camp, wiping them out entirely, much like a razor strips all hair from the skin [רד״ק, אבן עזרא, אברבנאל]. Alternatively, this imagery describes a massive military invasion by Assyrian troops that flooded and ruined the land. Just as a razor cuts close to the flesh without actually penetrating it, the enemy besieged the land and caused heavy damage, but did not completely conquer or exile the nation [שד״ל].
The specific nature of this razor carries significant meaning. It is described as a hired tool, implying it is exceptionally sharp, much like the instrument of a professional barber [אבן עזרא, רד״ק, מצודת דוד]. Historically, this alludes to King Ahaz of Judah, who paid a bribe to hire the King of Assyria for military assistance [שד״ל]. Another approach understands this description not as a hired tool, but as an expression of greatness and profound importance [רש״י, מצודת ציון, מלבי״ם]. The forces wielding this razor arrived from across the river [רד״ק], or earned this association because the Assyrian camp was stationed right along the riverbank [אברבנאל].
The metaphor divides the shaving into three distinct areas of the body, representing the different social classes affected within the Assyrian army. The head symbolizes the army commanders, leaders, and prominent figures [רד״ק, מצודת דוד, אבן עזרא]. Some identify the head specifically as Sennacherib, the King of Assyria [רש״י], or as the great sinners whose transgressions were public and widely known [מלבי״ם]. The hair of the legs, often understood as a polite euphemism for pubic hair, represents the common masses and simple soldiers [רד״ק, אברבנאל, מצודת דוד], or those who sinned in secret [מלבי״ם]. Others suggest this refers literally to leg hair, which was shaved because the soldiers walked barefoot, or that it serves as a metaphor for the broader military camps [רש״י, שד״ל].
Finally, the imagery moves to the beard, emphasizing total destruction and finality [רש״י, מצודת ציון]. Unlike the hair of the head and legs, which is regularly cut, shaving a beard is considered a profound disgrace and humiliation, as a beard is grown as a symbol of honor and glory [רד״ק, מלבי״ם, שד״ל]. The beard represents the most important ministers [רש״י, אברבנאל] or the righteous individuals who perish alongside the wicked when a destructive force is unleashed without distinction [מלבי״ם]. The language describing the beard shifts from mere shaving to complete destruction. This change in tone hints at the ultimate downfall of King Sennacherib. He did not die in the initial plague with his army; rather, he met his end later when he was assassinated by the sword of his own sons upon returning to his homeland [רד״ק, מצודת דוד, אברבנאל]. There is also a tradition that his beard was literally singed and burned by fire [רש״י]. Ultimately, the King of Assyria, who arrived with terrifying military might, departed from the campaign entirely cut down, shaved, and utterly destroyed [ביאור שטיינזלץ].