‘For my sword has drunk its fill in heaven.
Behold it will come down on Edom,
And on the people of my curse, to judgment.
The sword of Yahweh is filled with blood, it is made fat with fatness,
With the blood of lambs and goats, with the fat of the kidneys of rams.
For Yahweh has a sacrifice in Bozrah,
And a great slaughter in the land of Edom.'
It is clear from this that the main verdict is against Edom and its neighbours, ‘the people of my curse' (compare Exodus 17:14; Exodus 17:16; Exodus 25:17-19; Deuteronomy 23:3-6; Nehemiah 13:1-3). Together they are the constituents of a great sacrifice when God will finally have His due because of their sinfulness. The time for mercy is past.
‘My sword has drunk its fill in heaven.' This may suggest that, like Daniel, Isaiah sees earthly nations as having counterpart angels in heaven (compare Isaiah 24:21). When Edom is to be slaughtered their heavenly counterparts must suffer first. Or it may be that the idea is that His sword has already drunk its fill in heaven in anticipation of what it is about to do.
The destruction of Edom is then likened to the offering of sacrifices, as being like a great holocaust (compare Ezekiel 39:17-19; Zephaniah 1:7-8). In such sacrifices the blood and the fat were offered to God (Leviticus 1:5-8; Leviticus 3:13-17 and often). The comparison brings out that this is not just arbitrary, it is necessary slaughter for the sins of the nations. They are receiving their due.
‘Bozrah.' Compare Amos 1:12 where it is described as a place of palaces. It is possibly modern Buseirah, a fortified city of nineteen acres on top of a crag at the head of the Wadi Hamayideh, sixty kilometres (thirty eight miles) north of Petra, and forty kilometres (twenty five miles) south-south-east of the Dead Sea, controlling the King's Highway, and thus probably prominent in denying earlier passage to the Israelites (Numbers 20:17).