Albert Barnes Commentary Psalms 45:3

"Gird thy sword upon thy thigh, O mighty one, Thy glory and thy majesty." — Psalms 45:3 (ASV)

Gird thy sword upon thy thigh - That is, arm or prepare yourself for battle and conquest. The Messiah is introduced here as a conquering king: one who is about to go forward to subdue the nations to himself, and one who is about to set up a permanent kingdom.

O most mighty - That is, Hero; Warrior; Conqueror.

With thy glory and thy majesty - With the glory and majesty appropriate to you, or which properly belong to you. This is at the same time the expression of a wish on the part of the author of the psalm, and a prophetic description. The psalmist desired that he would thus go forth to the conquest of the world; and saw that he would do it. Compare Psalm 45:5-6. It is needless to remark that this is easily and naturally applicable to the Messiah—the Lord Jesus—as going forth for the subjugation of the world to the authority of God. Compare 1 Corinthians 15:25 and 1 Corinthians 15:28. See also, in reference to the figure used here, Isaiah 49:2; Hebrews 4:12; Revelation 1:16; and Revelation 19:15.