First, let’s define what a coat of arms is before someone thinks we are talking about Burlington Coat Factory. A coat of arms is a shield of sorts. It is used to cover, protect, and identify the wearer. Historically, though the origination is linked back to the Middle Ages when armor bearings were given to soldiers and nobility, an ecclesiastical heraldry was also developed for clergy, giving way to the papal coat of arms.
Popes often use their own family shield or otherwise create their own, made up of a specific shape (the chalice being the most commonly used shape in ecclesial heraldry), several important symbols and surrounded by elements that indicate the person’s dignity, rank, title, jurisdiction and more.
Let’s take Benedict XVI’s papal coat of arms as an example.
Taken from the Vatican’s website:
The shield chosen by Pope Benedict XVI is very simple: it is in the shape of a chalice, the most commonly used form in ecclesiastical heraldry.
The field of Pope Benedict XVI’s shield, different from the composition on his shield as Cardinal, is now gules (red), chape or (gold). The principal field, in fact, is red.
In each of the upper corners there is a “chape” in gold. The “chape” [cape] is a symbol of religion. It indicates an idealism inspired by monastic or, more specifically, Benedictine spirituality. Various Orders and Congregations, such as the Carmelites and the Dominicans, have adopted in their arms the form of the “chape”, although the latter only used it in an earlier form rather than their present one. Benedict XIII (1724-1730) of the Order of Preachers used the “Dominican chief” [heraldic term: upper part of the field] which is white divided by a black “chape”.
Pope Benedict XVI’s shield contains symbols he had already used in his arms when he was Archbishop of Munich and Freising, and subsequently as Cardinal. However, they are arranged differently in the new composition.
The principal field of the coat of arms is the central one which is red. At the point of honour of the shield is a large gold shell that has a triple symbolism.