He shall judge among the nations. This is clearly not yet fulfilled. How God shall ultimately "judge among the nations," or rather "between nation and nation," is a mystery which only the future can reveal.
It has been supposed that "by his providential retributions he will decide those international questions out of which war ordinarily springs" (Kay). But it would seem to be at least as likely that he will bring the nations to such a pitch of wisdom and moderation, that they will voluntarily discard war, and agree to decide any disputes that arise by means of arbiters.
The arbiter would then, like other judges, represent God, and "by him decree justice" (Proverbs 8:15). Shall rebuke. Rosenmüller translates, "Arbiter pacts sit;" Cheyne, "shall arbitrate." Here again, as in Isaiah 2:3, "people" should be "peoples."
They shall beat, etc. On a sudden call to war, nations "beat their ploughshares into swords, and their pruning-hooks into spears" (Joel 3:10). They will do the reverse "in the latter days," when God shall have "made wars to cease" (Psalms 46:9) and "speak peace unto the nations" (Zechariah 9:10).