Radak

But Thou, Lord, art a shield about me: – the opposite of their words who are saying that there is no hope for me in this world, nor in the world to come. Thus they are thinking and saying; but Thou wilt deal with me in the very opposite way and wilt be a shield about me to deliver me in this world and a shield about me in the world to come. My glory: – The “glory” is the soul, as “and my glory rejoiceth” (Ps. 16:9); “in order that (my) glory may sing praise to Thee” (Ps. 30:13), and (the word) “shield” which he has already used is to be understood here, “a shield about me” and “a shield of my glory.” Or the interpretation of my glory may be: the opposite of the dishonour which was his as a fugitive. and the lifter up of mine head: – so that I shall not be put to shame nor my countenance fall before my enemies, but I shall walk erect and with uplifted head; for when Thou deliverest me they will recognise and know that Thou hast pardoned me the iniquity through this punishment with which Thou dost punish me.