The lemma (root word) for κεχαριτωμένη (kecharitomene) is χαριτόω (charitóō). It is interesting that the word charitóō is used in only two places in the Scriptures. One is in Luke 1:28 (highly favored); the other is in Ephesians 1:6 (made us accepted).
It's curious how God, who inspired St. Paul to use those words to describe what He did for us, inspired St. Luke to record the words of the angel when he saluted Mary. And that these words would be used nowhere else in Scripture.
You know what is even more curious is that God never inspired St. Paul to write any of the Mary doctrine to all these churches. It was almost as if these Mary doctrines were not all that important. That is what is real curious.