Who will judge?
Radak: The judge, i.e. Melech ha'Mashi'ach. [The subject is omitted,] like "va'Yaged l'Yakov" and "va'Yomer l'Yosef" Bereishis 48:2, 1) ? the one who told him, and similar verses.
How will he be Shofet Bein Amim?
Rashi: This is an expression of rebuke.
Radak citing Targum Yonasan: If there will be war or claims between nations, they will come for judgment to Melech ha'Mashi'ach. He will be master over all the nations, and will rebuke them. The one who did improperly, he will tell him to fix his misdeed against his opponent. There will not be war between nations, for he will make peace between them!
Malbim: He will nullify the two reasons for war. (a) Sometimes they fight due to difference of creed or Emunah. "Ki mi'Tziyon Tetzei Sorah" ? there will be no differences. (b) There are claims between countries. "He will judge between nations and rebuke", and return them to straightness.
What are "Itim"?
Rashi (Yeshayah 2:4): They are plowshares.
Radak: They are shovels used to dig.
What are "Mazmeros"?
Rashi (Yeshayah 2:4): They are scythes used to prune vineyards. Radak - this is like "v'Charmecha Lo Sizmor" (Vayikra 25:4).
