Grace (style)

His Grace or Her Grace is a style of address used for various persons. It was the style used to address the King or Queen of Scots up to the Act of Union of 1707. It was also used to address monarchs of England before Henry VIII. Today, the style is used when referring to dukes and duchesses in the United Kingdom, who are not members of the royal family. "Your Grace" would be used in spoken or written address. Royal dukes, for example The Duke of York, are addressed with their higher royal title, "Royal Highness".
Ecclesiastical usage.
The style "His Grace" and "Your Grace" is used in England and other English-speaking countries to address Roman Catholic archbishops. This is not common in other countries (for example in France and the United States Roman Catholic bishops are addressed using the style "Excellency"). In the Eastern Orthodox Church it is used for bishops and abbots. The style is also used for an archbishop and some bishops in the Anglican Church. In the United Methodist Church in the United States, bishops are addressed "Your Grace" (spoken style, and "His/Her Grace" (reference style). In the Church of God in Christ, the Presiding Bishop's style is "His Holy Grace" and "Your Holy Grace". The bishop's reference style is "His Eminence" and the spoken style is "Your Eminence". 
International Society for Krishna Consciousness (ISKCON—Hare Krishna) devotees prefix the name of their founder, A.C. Bhaktivedanta Swami Prabhupada, with "His Divine Grace".
In Islam several Sufi orders (such as the Qadrianis and Hawariyun) may refer to their spiritual Grand Masters with the epithet "(Most) Graceful ..." or "His Grace" in reference style while the spoken style is "(Most) Graceful".