“glorious throne.” This is an example of the Figure of Speech antimereia (of the noun in regimen for an adjective. Bullinger, Figures of Speech Used in the Bible). The Greek literally reads “a throne of his glory.” “Glory” is moved by antimereia from an adjective to a noun to give it more emphasis. Unfortunately, in English, it makes the sentence hard to understand, so using the simple adjective makes sense.
Jesus will come in his glory at the Battle of Armageddon, at which point he will conquer the armies of the Antichrist, Satan will be imprisoned, and Jesus will rule over the earth (Rev. 19:11-20:3). For the Sheep and Goat Judgment, Jesus will set up his throne in the “wilderness of the people” which is between Egypt and Israel (see commentary on Matt. 25:32).