Adam Clarke on Psalms 45:3

Gird thy sword upon thy thigh, O most mighty - This clause should be translated, O hero, gird thy sword upon thy thigh! This, I think, cannot be spoken of Solomon. He was not a warlike prince: he never did any feats of arms. It has been said he would have been a warrior, if he had had enemies; it might have been so: but the words more properly apply to Christ, who is King of kings, and Lord of lords; whose sword with two edges, proceeding from his mouth, cuts all his adversaries to pieces.

With thy glory and thy majesty - Be as war-like as thou art glorious and majestic. Solomon's court was splendid, and his person was majestic. These words may be well said of him. But the majesty and glory of Christ are above all: he is higher than all the kings of the earth; and has a name above every name; and at it every knee shall bend, and every tongue confess.