Jamieson, Fausset and Brown on Isaiah 34:5

5. sword--(Jr 46:10). Or else, knife for sacrifice for God does not here appear as a warrior with His sword, but as one about to sacrifice victims doomed to slaughter [Vitringa]. (Eze 39:17).

bathed--rather "intoxicated," namely, with anger (so De 32:42). "In heaven" implies the place where God's purpose of wrath is formed in antithesis to its "coming down" in the next clause.

Idumea--originally extending from the Dead Sea to the Red Sea; afterwards they obtained possession of the country east of Moab, of which Bozrah was capital. Petra or Selah, called Joktheel (2Ki 14:7), was capital of South Edom (see on Is 16:1). David subjugated Edom (2Sa 8:13, 14). Under Jehoram they regained independence (2Ch 21:8). Under Amaziah they were again subdued, and Selah taken (2Ki 14:7). When Judah was captive in Babylon, Edom, in every way, insulted over her fallen mistress, killed many of those Jews whom the Chaldeans had left, and hence was held guilty of fratricide by God (Esau, their ancestor, having been brother to Jacob): this was the cause of the denunciations of the prophets against Edom (Is 63:1, &c.; Jr 49:7; Eze 25:12-14; 35:3-15; Joe 3:19; Am 1:11, 12; Ob 8, 10, 12-18; Mal 1:3,4). Nebuchadnezzar humbled Idumea accordingly (Jr 25:15-21).

of my curse--that is, doomed to it.

to judgment--that is, to execute it.