1)
What are "Zikim"?
1.
Rashi: They are fetters.
2)
Why will they fetter the kings and nobles?
1.
Radak: It is to take vengeance on them in their lifetimes.
2.
Malbim: This refers to the kings of the seven Kena'ani nations, in order to fulfill "v'Nasan Malcheihem b'Yadecha v'Ha'avadta Es Shmam" (Devarim 7:24).
