1)
Which day is discussed?
1.
Radak: It is the day when the 10 tribes were exiled; that was the honor of Yakov.
2)
What is "Yidal"?
1.
Radak, Malbim: It will become poor; it is the opposite of honor, for with wealth is honor.
3)
What is the meaning of "u'Mishman Besaro Yerazeh"?
1.
Rashi citing Targum Yonasan: The wealth of its honor will be exiled.
2.
Radak: This is a metaphor for their wealth and honor that was exiled. Razon is the opposite of Mishman (fat).
3.
Malbim: Its people will be diminished; they will be few.