1)
The previous verse said that Se'ir will be Shemamah. What does our verse add?
1.
Radak: The name of Se'ir will be finished wherever they are.
2.
Malbim: Verse 3 discusses of Nebuchadnetzar; our verse discusses the Churban via Beis Chashmona'i.
2)
Why does it say "va'Yadata Ki Ani Hashem"?
1.
Malbim: Then, [Edom] circumcised, immersed, accepted Hashem's Elokus and converted.
