Ch. 33 concludes, or so the commentary claims, the initial portion of Isaiah son of Amoz’s prophecy with a counterpoint to the opening message in 1:21-27. One interesting thing that I’ve noticed today is the focus on individual salvation: vv. 14-16 note the distinction between sinners and the righteous in the same holy city of Zion. Much of the OT imparts salvation and judgment on entire people-groups rather than individuals. After noticing this, though, and flipping back to ch. 1 to compare the intro and end of this section, I see that similar wording exists there bestowing the fruits of actions on individuals.
Ch. 34, then, may well have been written during or after the Babylonian exile. Apparently the Edomites inflicted unusually harsh treatment on the Jews during this period, hence this psalm or prayer against them. The prophecy failed to play out in exactly the manner predicted, though (at least according to the JSB – I have not verified this with any other sources): Far from being slaughtered, by the 2nd c. BC the Edomites were known by their Greek name Idumeans, and by and large they converted to Judaism with passionate endurance during the Roman occupation.