Coat of arms of the U.S. bishop Gregory John Hartmayer, Bishop of Savannah.
Motto: Pax et Bonum – Peace and Good – are the words that were used by St. Francis in his greetings to others. It embodied the simplicity and goodness he saw in all of God’s Creation.
Blazon: Impaled, at dexter (for Savannah), argent on a cross gules a rose or between four mullets azure and at sinister (for Bishop Hartmayer), per pale argent and azure a chief wavy of one crest depressed in the center of one point and issuant in base throughout a pile reversed enarched all counterchanged, overall an eagle or and in chief at dexter a triquetra interlaced with circle of the last and at sinister a tau cross sable.
Significance: The Episcopal heraldic achievement, or bishop’s coat of arms, is composed of a shield, with its charges, a motto scroll, and the external ornaments indicating office. The shield is explained (in heraldic terms, blazoned) in twelfth century language and articulated as if it is being given to the bearer who will wear it on his arm. Thus, it must be remembered where the terms dexter (right) and sinister (left) are used, they are in fact, reversed as one view the shield from the front.
It is Church tradition that when a Bishop becomes the Ordinary of a Diocese, the arms of his jurisdiction are joined (impaled) with his personal coat of arms. The Coat of Arms of the Diocese of Savannah appears in the dexter impalement (left side for the viewer) whilst that of Bishop Hartmayer appears in sinister (right side for the viewer). This custom of combining the two is meant to show the spiritual unity shared between the Bishop as Shepherd and the Diocese as his Flock – so core to the theology of being a Bishop - that he also wears a ring on his right hand as a symbol of this union.
The Coat of Arms for the Diocese of Savannah is a cross of red on silver background. The cross is in fact the Cross of St. George. This symbolizes the state of Georgia, which was named for King George II. The four blue stars signify that Georgia was the fourth state to ratify the Constitution of United States. The gold rose found in the middle of the cross is the Cherokee rose, the state flower of Georgia, and is also associated with the Rose of Sharon as well as Mary, the Mystical Rose.
The personal Coat of Arms of Bishop Hartmayer is intended to symbolically represent the Bishop’s heritage and vocation as a Conventual Franciscan Friar. The background of wavy blue and white is a heraldic symbol for water. The Bishop is a native of Buffalo, NY – the Queen City of the Great Lakes. Water is also the key symbol of Baptism – the first Sacrament of Initiation as a Christian. This helps recall the Bishop’s ministry as the primary sacramental minister of his diocese. The eagle serves as a two-fold symbol of both the Bishop’s German heritage and of St. John the Evangelist. The Bishop’s father was named John and this is the Bishop’s middle name. The Celtic Knot, known as a Triquetra, represents the Bishop’s Irish heritage on his maternal side. And finally, the Tau is a reference to Bishop Hartmayer’s vocation as a Conventual Franciscan Friar. St. Francis would sign his writing with a Tau, often painted it on the walls and doors of places and he stayed, and would remind his friars that their habit was in the shape of a Tau cross illustrating to them that they must go into the world wearing this cross like an incarnation of Christ.
Behind the arms is placed a gold processional cross - the symbol of Episcopal office. For the processional cross, Bishop Hartmayer has selected the Cross of San Damiano. The entire Franciscan movement began when St. Francis, whilst praying at the Chapel of San Damiano, heard the crucifix speak to him and say, “Francis, go rebuild my Church for it is falling to ruins.” St. Francis thought this was a literal command to rebuild the chapel that was in disrepair. Soon, however, he realized God was asking more of him.
Surrounding the shield and processional cross is the pontifical hat with six tassels on each side disposed in three rows, all in green. These are the heraldic insignia of a prelate of the rank of bishop in accordance with the Instruction of the Holy See, dated 31 March 1969. Before 1870, the pontifical hat, known as a galero, was worn at solemn cavalcades held in conjunction with papal ceremonies. The color of the hat and the number of tassels were signs of the rank of the prelate, a custom still preserved in ecclesiastical heraldry. 
Reference:

diosav.org
Own work
SajoR