What is the meaning of "v'Samti Mishpat l'Kav"?
Rashi: Before that king comes, I will bring decrees on them to finish off the sinners. I will place Mishpat of his afflictions to be to a Kav. I.e. I will set a line for the level of afflictions. Mishpat is an expression of justice.
Radak: Through the king [that I will establish], I will make Mishpat stringent like a line to straighten a building - unlike now, that there is no Mishpat, no Chesed and no knowledge of Elokim.
Malbim: Builders, after laying the cornerstone, draw a line for the length and width of the building. Mishpat between people will be the Kav for the length and width of the building Beis Yehudah.
What is "Tzedakah l'Mishkales"?
Rashi: Mishkales is the plumb-line used to even the building 1 . Tzedakah will go in front of them and straighten their ways; sinners will perish, and Tzadikim will remain.
Malbim: Builders, after building the height, use a plumb-line to check that the height is equal on the [entire] wall. Tzedakah - good deeds Bein Adam la'Makom - will be the plumb-line via which the building will go up opposite Hashem. Via Mishpat they will succeed naturally, and via Tzedakah, supernaturally.
Radak: It is of tin or lead. It tests whether the building is straight, and based on it, they straighten it. So Tzedakah will be straight! Mishkales has the same grammatical form as Mishmeres; the Asnachta changed the vowel under the Kuf to a Kamatz.
What is the meaning of "v'Ya'ah Varad Machseh Chazav"?
Rashi: You said "Samnu Chazav Machsenu" (15) - hail will sweep away that cover. Ya'ah is an expression of sweeping, like "Es ha'Ya'im", which are used to sweep oven ash.
Radak: The enemy is compared to hail and flooding water - "k'Zerem Mayim Kabirim Shotefim" (2).
Malbim: After they will build the Mivtzar, they will abolish the Machseh, which is nothing; they will not trust in Ashur and Egypt.
Why does it say "v'Seser Mayim Yishtofu"?
Rashi: You said "uva'Sheker Nistarnu" (15) - hail will wash away that protection. I.e. I will bring multitudes that will break their altars and idols.
Radak: This hints to Machaneh Ashur, which will come like flooding water - "Es Mei ha'Nahar ha'Atzumim veha'Rabim" (8:7). It says "v'Chalaf bi'Yhudah Shataf v'Avar
