What is "Nehe"?
Rashi: Cry and lament.
Radak: This is like "Sa Kinah" (2). The Navi does not lament over them ? he rejoices over their Churban and eradication! Rather, he says the words in which the lamenters will lament.
What is the significance of lowering Egypt and Bnos ha'Goyim?
Rashi: Prophesize about them, and about all who deny the Nevu'ah, that they will descend to Gehinom.
Radak #1: Via your words and Nevu'ah, make them descend from their grandeur, and descend further to Eretz Tachtiyos, and perish there. "Bnos" are congregations, like Bas Edom, Bas Bavel.
Radak #2: "Horidehu" is [lamenting,] like "Arid b'Sichi" (Tehilim 55:3).
Malbim: The verse depicts that Egypt does not want to descend to the pit. It did not come to fight with Edom! However, lament over it and make it descend Bal Korcho (against its will). Afterwards will descend Bnos of Goyim Adirim, e.g. Edom, and Egypt's helpers Ashur and Eilam.
