What are "Chitzecha Shinunim"?
Rashi: Talmidim are called Chitzim 1 - "k'Chitzim b'Yad Gibor Ken Bnei ha'Ne'urim" (127:4).
Radak: Your arrows are sharp, and not blunt.
Malbim (Derech ha'Muskal): The enemies of the intellectual Nefesh - the powers of imagination, excitement and lust - one must fight them with arrows and weapons to make them obey the intellect. They will think in their hearts that your arrows are sharp to the point that nations will fall under you. When intellect reaches clarity, laws of Chachmah are engraved constantly on the tablet of his heart. The Nefesh receives a second nature, that pictures only good images and Yir'as Hashem. The Nefesh's enemies cannot oppose it - "Tovah Chachmah mi'Klei Kerav" (Koheles 9:18).
"Shinunim" means sharp. (PF)
What is the meaning of "Amim Tachtecha Yiplu"?
Rashi: In the reward of Torah, the idolaters will fall under Yisrael. The verse should be re-arranged 1 .
Radak: "Yiplu" refers to what follows this (in the enemies' hearts). This is why there is a Sheva under the Pei, even though the note is Asnachta 2 . Some say that Yiplu applies also to what came before (nations will fall under you).
Malbim: The verse should be re-arranged. The hearts of Oyvei ha'Melech (your enemies) will think that your arrows are sharp, so nations will fall under you, and they will fear to rebel.
I.e. normally the Asnachta should change it to Yipolu (like in Yeshayah 3:25). It does not, for this is not a proper Asnachta, which totally ends the first half of the verse. (PF)
Who are "Oyvei ha'Melech"?
Rashi: Chachamim determining the Halachah are called enemies of each other at the time - "Lo Yevoshu Ki Yedabru Es Oyvim ba'Sha'ar" (ibid., 5).
Radak: They are Mashi'ach's enemies.
