What "Sha'on" will rise?
Rashi: The voice of the vanquished - flee, flee!
Radak: Enemies will come against them to destroy them. This is like "v'Sha'on l'Umim ki'Sh'on Mayim Kabirim" (Yeshayah 17:12).
Radak citing Targum Yonasan: A great clamor will rise against your nation.
Malbim: It is rebellion against their kings.
Why does it say "b'Amecha" with a Yud (plural)?
Radak: It refers to all the Shevatim.
What is the meaning of "v'Chol Mivtzarecha Yushad"?
Radak: All the fortresses that you trust in them, each will be plundered via the enemy that comes upon you. The root of Yushad is Shadad; the Dagesh [in the Shin] is in place of the omitted Dalet.
Malbim: Amidst the quarrel between them, the fortresses were handed over to the enemy.
What is "k'Shod Shalman Beis Arbeil"?
Rashi: Like plunderers who come suddenly upon a nation dwelling in Shalom, via an ambush - they were not careful to flee from them; the plunderers take everything. Yonason translates "Beis Arbeil" to be Beis Ma'arav (the place of the ambush). The Aleph and Lamed at the end of Arbeil are extra. This is like Yizre'el, which is not the name of a city, yet the verse refers to it as the name of a city - "Ya'anu Es Yizre'el" (2:24).
Rashi citing Dunash: It is the name of a place.
Radak: Shalman was a known enemy in those days. He came suddenly to Beis Arbeil and plundered it. He felled the mother on her children, and did not leave a remnant. Arbeil is the name of a great man in those days.
Radak citing his father: Shalman is Shalman'eser Melech Ashur. Beis Arbeil is Shomron - the house that Kel Arav (ambushed), and seized it for its sin.
Malbim #1: Shalman is Shalman'eser Melech Ashur. Beis Arbeil is the name of a fortress in Malchus Efrayim.
Malbim #2: The fortress was handed over [to the enemy] in Shalom (without fighting. Even so, the enemy) conducts with people of the fortress as if they took it via ambush on a day of war, and kill Em Al Banim (the entire nation).
Why does it say "b'Yom Milchamah"?
Malbim: On the day of war, the fortress was handed over to the enemy via the rebellion and inner strife.
What is "[Em Al Banim] Rutashah"?
Rashi #1: It is cleaved. The same applies to "Ne'arim Teratashnah", "v'Oleleihem Yeruteshu" (Yeshayah 13:18, 16).
Rashi #2: It is abandoned, like Nutashah. Radak - so Chazal said (Bava Metzi'a 39a). The Targum of "Tishmetenah u'Ntashtah" (Shemos 23:11) is Tirteseshenah. They abandoned their wives and children, and left due to the sword and hunger. Rutashah is willingly; Netushim is Bal Korcham (against their will).
Radak: It is casting to the ground -"v'Oleleihem Yeruteshu" (Yeshayah 13:18, 16). A mother has mercy on its children when others want to kill them - it casts itself on them [to protect them].