Rashi: They will fear when I cast [from Shamayim] the Sarim of Ashur and Bavel. Malbim - the verse depicts that every nation has a root in Shamayim from which it draws its influence, power and existence. These are Sarei ha'Am. If the nation falls below, and the root remains in Shamayim, it is like a tree that was cut, and its root remains. It will return to sprout from below. Here, also the root will wilt, like flesh wilts without life.

Radak: This is a metaphor. When great affliction comes upon a person, it is as if Shamayim and Eretz were reversed on him. It is as if there are no Heavenly legions, for he has no light, and the world is dark. We find this parable often in Nevi'im.

Rashi: It is an expression of rolling. Now, there is good and light for Resha'im. When they will be stricken and destroyed, the world will appear dark on them, as if the sun and light were rolled, like a Sefer is rolled ¹ . Radak - Shamayim is [normally] stretched like an [open] Sefer.

Rashi citing Targum Yonasan: They will be wiped out from under Shamayim, like it says about them in the Sefer.

Malbim: The early nations, Shamayim was like a book for them. Through astrology, they saw the future. Every land was associated with a particular star. Now that their shade is removed, the Sefer is rolled [shut], and the readers cannot open it to read it.

Malbim: These are the legions below attributed to Tzeva ha'Shamayim and under their rule.

Rashi: It is wilting.

Malbim: This is like a tree - its leaves wilt when its roots decay.

Malbim: The vine leaf is first to fall. If the root lacks a little moisture, the leaves fall, for they are weak. So the Nochrim will faabo ll immediately.

Rashi: Wilting on a tree is called Noveles. Chazal said (Brachos 40b), Novlos are Bushlei Chunra ¹ . I.e. they ripen in the basket after they were picked. One gathers them, and they get heated and ripen.

Radak #1: It is like an Aleh ² (leaf) that falls from a fig tree.

Radak #2: It is like a fig that falls from a fig tree. It is called Te'enah, just like the tree. Therefore, there was no need to specify what fell; mi'Te'enah suffices. Malbim - a fig that falls is worse than a leaf that falls, for it spoils immediately due to much honey [in it]; it is not proper [to eat] at all (Ma'aseros 3:4). A leaf that falls, it does not spoil, and it is slightly proper to eat (Shevi'is 9:6). Therefore, it says that after they fall, they will be like "k'Feger Muvas" (14:19; like a dead body that was trampled).