Isaiah 34:6

6 A sword [is] to Jehovah -- it hath been full of blood, It hath been made fat with fatness, With blood of lambs and he-goats. With fat of kidneys of rams, For a sacrifice [is] to Jehovah in Bozrah, And a great slaughter in the land of Edom.

Isaiah 34:6 Meaning and Commentary

Isaiah 34:6

The sword of the Lord is filled with blood
Multitudes being slain by it; the "Lord" here is that divine Person that is described as a warrior, as a General of an army, with a sharp sword, by whom many are slain, such a number as that it is filled with the blood of them, ( Revelation 19:11-16 Revelation 19:21 ) : it is made fat with fatness:
not only filled with the blood, but fattened by it; the allusion is to ravenous creatures gorged and sated with the blood of others, and thereby made fat; perhaps this may refer to Christian princes, the sword in the hand of the Lord, who shall be enriched with the plunder and spoil of the antichristian states: [and] with the blood of lambs and goats, with the fat of the
kidneys of rams.
The Targum is,

``with the blood of kings and governors, with the fat of the kidneys princes;''
and Jarchi interprets them, of princes and rulers; but rather the common people are designed, or the common soldiers in the army, or however the inferior officers of it; kings, princes, and generals, being intended in the following verse ( Isaiah 34:7 ) . It denotes the great carnage of all sorts and ranks of men made at this time, and which is described in ( Revelation 19:18 ) : for the Lord hath a sacrifice in Bozrah, and a great slaughter in
the land of Idumea:
there seems to be two Bozrahs the Scripture speaks of, the one in Moab, ( Jeremiah 48:24 ) and another in Edom, ( Isaiah 63:1 ) which is here meant, and was a chief city of the Edomites, and signifies a fortress, being no doubt a place well fortified; this is the Bostra of Ptolemy F11, and which he places in Arabia Petraea. Aben Ezra says that some interpret it of Constantinople, the metropolis of the Ottoman empire; but it is best to understand it of Rome, as Menasseh ben Israel F12 does, and Idumea of the whole Roman jurisdiction; Rome being the chief city of the antichristian states, that great city, which John in his Revelation describes as reigning over the kings of the earth; here and in all the antichristian kingdoms will be a great "slaughter" of men, called a "sacrifice" of the Lord, because by his order and direction, and for the honour of his justice, and being acceptable to him; and perhaps there may be an allusion to the blood sacrifices being the Lord's; this slaughter and sacrifice is called the supper of the great God, ( Revelation 19:17 ) .
FOOTNOTES:

F11 Geograph. l. 5. c. 17.
F12 Spes Israelis, sect. 30. p. 91.

Isaiah 34:6 In-Context

4 And consumed have been all the host of the heavens, And rolled together as a book have been the heavens, And all their hosts do fade, As the fading of a leaf of a vine, And as the fading one of a fig-tree.
5 For soaked in the heavens was My sword, Lo, on Edom it cometh down, On the people of My curse for judgment.
6 A sword [is] to Jehovah -- it hath been full of blood, It hath been made fat with fatness, With blood of lambs and he-goats. With fat of kidneys of rams, For a sacrifice [is] to Jehovah in Bozrah, And a great slaughter in the land of Edom.
7 And come down have reems with them, And bullocks with bulls, And soaked hath been their land from blood, And their dust from fatness is made fat.
8 (For a day of vengeance [is] to Jehovah, A year of recompences for Zion's strife,)
Young's Literal Translation is in the public domain.