Charles Ellicott Commentary Psalms 45:3

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

Gird your sword ... O most mighty. —Or, perhaps, Gird on your sword in hero guise; or, Gird on your hero’s sword. The object of the poet’s praise is as heroic in war as he is beautiful in person.

With your glory and your majesty. —This adverbial use of the accusatives may be right, but it seems better to take them in apposition with sword. His weapon was the monarch’s glory and pride. Some commentators see here a reference to the custom of girding on the sword said to be still observed at the elevation to the throne of a Persian or Ottoman prince. But the next verse shows that we have rather an ideal picture of the royal bridegroom’s prowess in war.