C. F. Keil and Franz Delitzsch on Psalms 21:5-6

Psa 21:5-6 (Hebrew_Bible_21:6-7) The help of God turns to his honour, and paves the way for him to honour, it enables him-this is the meaning of. Psa 21:6 - to maintain and strengthen his kingship with fame and glory. שׁוּה על used, as in Psa 89:20, of divine investiture and endowment. To make blessings, or a fulness of blessing, is a stronger form of expressing God’s words to Abram, Gen 12:2 : thou shalt be a blessing i.e., a possessor of blessing thyself, and a medium of blessing to others. Joy in connection with (את as in Psa 16:11) the countenance of God, is joy in delightful and most intimate fellowship with Him. חדּה, from חדה, which occurs once in Exo 18:9, has in Arabic, with reference to nomad life, the meaning “to cheer the beasts of burden with a song and urge them on to a quicker pace,” and in Hebrew, as in Aramaic, the general signification “to cheer, enliven.”