The following commentary is by Blessed Theophylact.
And in the sixth month the angel Gabriel was sent from God unto a city of Galilee, named Nazareth, to a virgin espoused to a man whose name was Joseph, of the house of David; and the virgin’s name was Mary. And the angel came in unto her, and said, Hail, thou that art highly favoured, the Lord is with thee: blessed art thou among women. And when she saw him, she was troubled at his saying, and cast in her mind what manner of salutation this should be. And the angel said unto her, Fear not, Mary: for thou hast found favour with God (Luke 1:26-30).
The sixth month means the sixth month after John’s conception. The Evangelist says that the virgin was betrothed to a man of the house of David, to show that she too was descended from the tribe and lineage of David. For it was the law that husband and wife should be of the same tribe and the same lineage. Because the Lord had once said to Eve, In sorrow thou shalt bring forth children, that sorrow is now removed by the joy which the angel offers to the woman, saying to her, Rejoice, though who art full of grace. Since Eve had been cursed, now Mary hears herself blessed. She considered in her mind what sort of salutation this might be surely not an unseemly and provocative greeting as from a forward man to a young maiden? Or was it perhaps a divine salutation, since God was mentioned together with the greeting, The Lord is with thee. First the angel calms the fear in her heart, so that she might hear the divine decision when she was peaceful and untroubled. While she was troubled, she would not be able to hear and understand clearly the things that would take place. When the angel said to her, Thou who art full of grace, it is as if he were saying, “Thou has found grace and favor in the sight of God, and thou art pleasing to God.” This is not out of the ordinary, for there were many other women who had found favor with God.
(Blessed Theophylact, Archbishop of Ochrid and Bulgaria. The Explanation of the Holy Gospel According to Luke. Chrysostom Press. 2007, 14-15)