What is the meaning of "v'Sal'o mi'Magur Ya'avor"?
Rashi: His strength will depart due to great fear.
Radak #1: He will pass to his strong rock and tower. He will not trust in himself until he is there, due to his great fear.
Radak #2: He will pass even his rock, due to his great fear, and flee further 1 .
Radak citing Targum Yonasan: His authority will depart due to fear.
Malbim: His rock, i.e. fortress, will be cut in half via the saw, It is as if a saw cut it in two. I.e. afterwards, all his fortresses were conquered.
What is the meaning of "v'Chato mi'Nes [Sarav]"?
Rashi: Due to the miracles that they will see that Hashem does for Yisrael.
Radak: This is like one who fears when he sees soldiers flee. So the remaining officers will fear from the plague that they will see.
Malbim: Until now, they raised a banner against all nations for war. Now, they fear when they see a banner of war.
What fire is in Tziyon?
Rashi: It is a fire prepared to burn them.
Radak: It is on the Mizbe'ach in the Beis ha'Mikdash. I.e. this will be for the honor of His Mizbe'ach and Mikdash.
Malbim: The verse depicts that Yisrael's light is fire. The light that illuminated for Chizkiyah was fire to consume Machaneh Ashur, until the fire and light was in Tziyon, where Chizkiyah dwelled.
What oven is in Yerushalayim?
Radak: It is to burn them.
Malbim: Sancheriv fell outside Yerushalayim, and was burned. It is as if the fire that he lit in Tziyon heated the oven and furnace in Yerushalayim. Sancheriv's camp, which was around Yerushalayim, was burned via its heat.