Acts Of Apostles 6:8 And Stephen, full of grace and fortitude, did great wonders and signs among the people.
Your scriptural example is not a greeting by an Archangel, as in a name. Simon name was changed to “Peter”. Mary was titled full of grace at the first encounter with Archangel Gabriel.
The argument that “full of grace” is used identically of both Mary and Stephen is not supported in the Greek.