It's possible you're thinking of a different play or character. Perhaps you're thinking of:
* King Edward IV in Richard III, who is portrayed as a sickly figure, but not necessarily a healer.
* King Edward VI in Henry VIII, who dies young and is not portrayed as having any healing abilities.
Why might Shakespeare have focused on a character with healing powers?
* To explore themes of faith and miracles: The idea of a king with healing powers would be a powerful symbol of divine favor and could be used to explore themes of faith, miracles, and the relationship between church and state.
* To create a complex character: A character with the power to heal would be a complex figure, grappling with the responsibilities and temptations that come with such power.
* To comment on the political climate: The ability to heal could be seen as a metaphor for political power and the potential for good or evil that it holds.
It's important to note that while Edward the Confessor was known for his piety and some historical accounts suggest miracles were associated with him, Shakespeare did not write a play about him specifically.
If you have more information about the play or character you're thinking of, I might be able to provide a more specific answer.