1)
How did Hashem's voice break Ashur?
1.
Rashi, citing Sanhedrin 95b: He opened their ears, and they heard the Shirah of the Chayos, and died.
2.
Malbim: It would have sufficed to break them, from fear.
2)
What is "ba'Shevet Yakeh"?
1.
Rashi: Ashur, which used to strike you with its staff (Malbim - "ba'Shevet Yekekah" (10:24)
2.
Radak: Hashem will strike Ashur with His staff.
3.
Radak citing Targum Yonasan: Ashur, which used to strike with a staff, now it will be broken. Ashur is called Shevet - "Hoy Ashur Shevet Api" (10:5).
