Theophylact of Ohrid

Moved by God, the children confess Jesus as King, coming "in the name of the Lord," that is, as God, and say: "peace in heaven." Otherwise put: the former enmity that we had with God has ceased. For there was no King-God on earth. But now, when God comes upon the earth, there is truly peace in heaven, and therefore "glory in the highest," since the Angels also glorify that unity and reconciliation which the King and God riding on the donkey has granted us. …

Commentary on Luke ↗

Bede

Above all the virtues they had seen, they said: Blessed is the King who comes in the name of the Lord. They had indeed seen many virtues of the Lord, but they were especially astonished at the resurrection of Lazarus, which had recently taken place, with the crowd bearing witness who had been with Him when He called him out of the tomb and raised him from the dead. For the prophet also came to meet him and the crowd, because they heard he had performed this sign. …

On the Gospel of Luke ↗

Bonaventure

Saying: Blessed, etc. After the devotion of those praising, there is described here secondly the sublimity of the divine praises. There is described, therefore, the excellent praise of Christ from the mouth of the crowds excellently praising Christ the King, both as regards the excellent person of the one coming and as regards the excellent efficacy of his coming. First, therefore, as regards the excellent person of the one who comes, it is said: Saying: Blessed is the king, who comes in the name of the Lord. …

Commentary on Luke, Chapter 19 ↗