Why does it say here "Hashem Tzevakos"?
Malbim: He rules over all legions.
How will Hashem be Margi'a the land?
Rashi: When Bavel falls, there will be rest and relief for everyone. Radak - Melech Bavel used to agitate the land and bombard nations.
What is the tense of "Hirgi'a" and "Hirgiz"?
Radak: They are Makor (like an infinitive); there is a Chirik under the Hei, like past tense. We find like this - "Ganon v'Hitzil Paso'ach v'Himlit" (Yeshayah 31:5), "Ad Hishmido Osach" (Devarim 28:48).
Targum Yonasan (of Hirgi'a Es ha'Aretz): 'L'Mitbar Reshi'ei Ar'ehon 1 .' Radak - this is like "Roga ha'Yam" (31:34). 2
Yonason writes 'l'Misbar' to translate "La'arotz" (Yeshayah 2:19 - to terrify), "Lishbor" (ibid., 14:25), Lamog (Yechezkel 21:20 - to melt [the hearts]), "Titz'ad" (Chabakuk 3:12 - You step), and "Leyados" (Zecharyah 2:4 - to cast). (PF)
Above (49:19), Radak said that "Roga" is cleaving or cutting off. (PF)