Oecumenius

Then it is said that seven trumpets were given to the seven angels so that they might sound them as a king takes his place. With these same trumpets, the dead were also about to be awakened; for the wise apostle to the Thessalonians, writing about divine matters, says in the first epistle that "the Lord Himself will descend with a command, with the voice of an archangel, and with the trumpet of God." (1 Thess. 4:16) And again, he says, "for the trumpet will sound, and the dead will be raised incorruptible." (1 Cor. 15:52)

Commentary on Revelation ↗

Bede

And I saw seven angels standing before God, etc. The Church, often commended by the number seven, is devoted to the duty of preaching, the first trumpet signifying the common destruction of the impious by fire and hail; the second, the devil expelled from the Church, more fervently inflaming the sea of the world; the third, heretics falling away from the Church, corrupting the rivers of the Holy Scripture; the fourth, the downfall of false brethren in the obscuration of the stars; the fifth, the greater infestation of heretics …

Commentary on Revelation ↗

Alcuin of York

And I saw seven angels standing in the sight of God; and there were given to them seven trumpets. And another angel came, and stood before the altar, having a golden censer. In this place he upsets the order of the narration and interposes something; for, as the following will show, the angel with the censer came and stood before the altar before they received the seven trumpets. He interposes something because he introduced this angel with the censer in the middle before he had finished talking about the others. …

Commentary On Revelation ↗