"According to a strong Jewish tradition, the image displayed on King David's shield was not, as many have assumed, a six-pointed star (the so-called Magen David) but a menorah inscribed with these words: 'May God be gracious to us, and bless us and make his face to shine upon us.' The menorah was likely the shield of David as well as the seal of Solomon. The Golden Menorah, published in Prague in the sixth century, declared, 'This psalm, together with the menorah, is an allusion to great things...King David used to bear this psalm inscribed, pictured, and engraved on his shield, on a sheet of gold, in the shape of the menorah, when he went forth to battle, and he would meditate on its mystery, and conquer," John D. Garr, God's Lamp, Man's Light: Mysteries of the Menorah, pg. 174So was the real shield of David a hexagram or a Menorah? Guess we may never know.
But, for our purposes, there's no reason to search for anything other than the Menorah. After all, the Menorah symbolizes Yeshua, the Light of the World. So why look for a better symbol?