Why is "Merivav" written without a Yud?
Refer to 2:9:1:1, 2.
Aderes Eliyahu: Even though each [fought Yisrael] in his own time, in the future Hashem will gather them and fight them together.
Who are "Merivav"?
Radak: They are people who feud with Tzadikim.
Ralbag, Malbim: They are those who will feud with Shmuel, i.e. the Pelishtim. (Now Chanah prayed for him.)
Rosh Hashanah 17a: They are heretics, Mosrim, Apikoros who denied Torah or Techiyas ha'Mesim, people who separate from Darchei Tzibur, people who put their fear on people, people who sinned and made the Rabim sin.
Why is "Alav" written without a Yud?
Rashi (from Midrash Shmuel 5:17): It can be read Alu - even if they ascended to Shamayim, Hashem will thunder on them and cast them down.
Why does it say "Alav" (singular)?
Radak: Hashem will do so to every one of them.
Bi'ur ha'Gra says that this hints to casting hailstones on Gog and Magog. Perhaps the verse alludes to their army in the singular. (PF)
Aderes Eliyahu: Hashem will cast on the head of Merivav.
Malbim: It means, for the sake of Shmuel.
Why does it say "ba'Shamayim"?
Radak #1: This is like mi'Shamayim, like "Yar'em Min Shamayim" (2:22:14). We find the prefix Beis in place of a Mem - "ba'Kadoshim Lo Sochal", "veha'Nosar ba'Basar uva'Lechem" (Vayikra 22:4, 8:32).
Radak #2: Hashem will make thunder in Shamayim to befuddle them. "Alav" means for the sake of [scaring] him. Thunder is a parable for decrees from Shamayim - "va'Yishlach Chitzim va'Yfitzem Barak va'Yahom" (2:22:15).
What is the meaning of "Hashem Yadin"?
Rashi: Hashem will judge and afflict them.
Malbim: [Chanah requested] 'Hashem - may Shmuel judge
What are "Afsei Eretz"?
Radak: They are at the end of the land, hidden places - "li'Ketzos ha'Aretz Yabit", "Im Yisaser Ish ba'Mistarim" (Iyov 28:24, Yirmeyah 23:24)
Bi'ur ha'Gra: After Gog and Magog, Hashem will gather and judge all the nations in Emek Yehoshafat (Yo'el 4:2).
Malbim: Shmuel will go around all of Eretz Yisrael [to judge them].
Who are Malko and Meshicho?
Bi'ur ha'Gra: Malko is Mashi'ach ben Yosef. Meshicho is Mashi'ach ben David - "Atzmi'ach Keren l'David" (Tehilim 132:17). Also "Magdil Yeshu'os Malko v'Oseh Chesed li'Meshicho" (Tehilim 18:51) refers to them.
Malbim: Malko is the king (Sha'ul) that Shmuel will anoint. Meshicho is when he will anoint David.
