1)
What are "Geva'os"?
1.
Rashi: This is an expression of high places.
2.
Malbim: They are [hills] around the mountains, and are smaller than them.
2)
What are "Ge'ayos"?
1.
Rashi: This is an expression of canyons.
2.
Malbim: Afikei Mayim (streams) go between mountains, and Ge'ayos between hills.
3)
Against what will the sword be sent?
1.
Radak (2): It includes the sword that will kill the worshippers, and destroy the Bamos and Mizbechos. Also a hammer is called Cherev ? "Ki Charbecha Henafta Aleha va'Techaleleha" (Shemos 20:22), "Yutatz b'Charbosav" (below, 26:9).