Why does it say "She'agah Lo k'Lavi"?
Rashi: This fear will be on you like [fear of] a lion.
Malbim: A Lavi (adult lion) roars stronger than a Kefir (young lion). A Kefir constantly roars, unlike a Lavi. [The enemy] will roar strongly, like a Lavi, and constantly, like a Kefir.
Why does it mention a Lavi and a Kefir?
Malbim: Refer to 5:29:1:2.
What is the significance of "Yinham v'Yochez Teref"?
Radak: A lion roars only when it holds prey - "ha'Yish'ag Arye ba'Ya'ar v'Teref Ein Lo" (Amos 3:4). When Melech Ashur came, he conquered all of Eretz Yisrael and the fortified cities of Yehudah.
Malbim: A lion groans only when it has no prey. [The enemy] will groan even though it has prey, for it will not be satiated.
What is the meaning of "Yaflit"?
Rashi: He will save [his prey for himself, from anyone who comes to save it].
Ibn Ezra: It will let go [of its prey, to see if anyone will come to save it; no one will come].
Radak: He will take the Peletah (remnant), i.e. Eretz Yehudah. [The first time he came, he conquered the 10 tribes. The second time,] he conquered all [of Yehudah], except for Yerushalayim.
Malbim: It will emit the prey to its holes, "and no one can save it", for no one can stand against it.