Why does it say "Ki Darachti Li Yehudah"?
Rashi: In the end, Bnei Yavan will take kingship from Malchei Paras, and they will do evil to you. I will draw Yehudah 1 to be for Me a bow of war, and they will fight the Yevanim in the days of Antiyochas.
Malbim: This was the first heralding. Bnei Yehudah will defeat Bnei Yavan via Hashem's salvation, miraculously.
Rashi (Devarim 33:11): Elazar and 12 Bnei Chashmona'i defeated Yavan. (They were Kohanim! Perhaps they are called Yehudah because they lived in Yehudah. - PF)
What is the meaning of "Keshes Mileisi Efrayim"?
Rashi: This is abbreviated. It means Keshes Mileisi Yad Efrayim, like "v'Yehu Milei Yado va'Keshes" (Melachim II, 9:24). Efrayim will be for Me like a quiver full of arrows. Radak - Milei Yado is drawing the bow with all one's strength, in order to shoot the arrow. Even though Efrayim and the other [of the 10] tribes were not in Bayis Sheni, a small amount of them remained in the land after the tribes were exiled in the days of Hoshe'a ben Elah 1 . We find in the days of Yoshiyah "mi'Yad Menasheh v'Efrayim umi'Kol She'eris Yisrael" (Divrei ha'Yamim II, 34:9). They were exiled with Yehudah and Binyamin, and returned with them when Yehudah and Binyamin returned.
Malbim: In the future, Bnei Efrayim (the 10 tribes) will be aroused to fight Gog and Magog.
About what will He arouse Bnei Tziyon?
Rashi: To fight Antiyochas' army.
Radak (10:12): To fight Gog and Magog. "Yavan" refers to them; Yavan and Magog were brothers, Bnei Yefes (Bereishis 10:2). All of them will come in the days of Mashi'ach. Targum Yonasan of "Al Banayich Yavan" is Al Bnei Amemaya.
Whom will Hashem make "k'Cherev Gibor"?
Radak: Bnei Tziyon - I will give to them strength to fight Bnei Yavan.
Malbim: Bnei Efrayim, against Gog and Magog.