My designer has recently gotten to do some minor work on some ecclesiastical heraldry. She didn’t design the whole thing, but she was brought on after the initial design work for some tweaking. When she told me, I immediately whipped out my heraldry books, but of course, I wasn’t needed. Nevertheless, I’ve gotten to do some peeking over shoulders, which has given me an interesting look at how modern ecclesiastical heraldry is created. 
Modern ecclesiastical heraldry is usually made without regard to the symbols associated with various colors, symbols, and shapes that came from medieval heraldry since need for the arms to be meaningful to the community that will be viewing them supersedes historic symbolism. Nevertheless, there is usually a great amount of overlap.
Where medieval arms usually feature a crown or a helmet, the arms for a diocese will feature a bishop’s miter. I think the reason for this is obvious. The arms of a bishop or cardinal will feature a pilgrim’s hat with different numbers and colors of tassels depending on rank. A cardinal’s arms will have 30 red tassels, an archbishop’s 20 green tassels, and a bishop’s 12 green tassels.  They will also feature either a shepherd’s crook or a processional cross (sometimes both).  Papal arms will include the keys of the Kingdom of Heaven.
Diocese of Dallas
These are the arms for the Roman Catholic Diocese of Dallas. The patron of the diocese is the Sacred Heart of Jesus, so the color for the shield is red. The crossed swords symbolize St. Paul, who died by the sword, and represent the mission in St. Paul, Texas, the first in that area. The star is for the Lone Star of Texas and will be recognizable to anyone who as seen a Texas flag. The wavy white line represents the Trinity River, a Texas river with a name important to Catholics. The three fleurs-de-lis likewise represent the Trinity and honor the French priests who served the diocese in its early days. 
Next, take the arms of the bishop of Dallas, Bishop Kevin Farrell. The diocese website has the bishop’s arms impaled (split) with the diocese arms, though Bishop Farrell does have his own arms without the diocese as well. His arms have a lion rampant (both front paws up) to honor Cardinal Theodore McCarrick, Archbishop Emeritus of Washington, and the O’Farrell clan (Bishop Farrell was born and raised in Dublin). The upper portion is gold and red for Cardinal McKerrick. The lower portion is gold for the O’Farrell arms, but where the O’Farrell arms would be green, Bishop Farrell’s arms are blue to represent Our Lady of Lourdes (Cardinal McCarrick ordained Bishop Farrell on her feast day). The white rocks at the bottom symbolize St. Kevin, who is Bishop Farrell’s patron saint. The Latin motto “STATE IN FIDE” translates to “stand firm in the faith,” from St. Paul’s letter to the Colossians. 
Archdiocese of Galveston-Houston
The shield for the Archdiocese of Galveston-Houston is blue with silver roses, both of which symbolize the Virgin Mary. The red cross symbolizes faith, while the red square with the white star symbolize Texas. Though not noted on the diocesan website, I find the silver roses particularly appropriate because the heraldic rose is five-pointed, making it suitable both for Mary and for Texas. 
The Archdiocese of Galveston-Houston is the seat of Cardinal Daniel DiNardo. His arms feature a green field for the maiden name of Cardinal DiNardo’s mother (“Green”). The field is split by a blue and white checked fess, taken from the arms of the Diocese of Pittsburgh where Cardinal DiNardo served as a priest. The silver bottle with the golden cross is a play on words. “DiNardo” means “of the nard/ointment,” so the placement of the cross on the bottle indicates that it is the Chrism, or the oil/ointment used in the anointing of priests. Cardinal DiNardo’s motto is “Ave Crux Spes Unica,” translated as “Hail, O Cross, Our Only Hope.” This phrase is taken from a Latin hymn by Venantius Fortunatus. 
I don’t have any official statements about how ecclesiastical arms are used these days. However, I can surmise that they’re used in about the same way as university arms. Obviously, they’re not taken into battle. They will appear on websites, letterhead, business cards, and perhaps the polo shirts of diocesan employees. They also appear in decorations, such as stained glass windows, decorative floor mosaics, or flags. The arms were once used for seals, but adhesive envelopes have made that practice obsolete.
The Church has always identified herself and instructed her people using symbols. I appreciate that this heraldry is still used today. The heraldry is an official statement of a bishop’s goals for his leadership. It combines the symbols that are of personal importance to him with the symbols that are important to his parishioners and becomes as recognizable as a signature. Pulling out my medieval heraldry books don’t do me much good here, but as a Texan, a Catholic, and a medievalist, I can appreciate these arms in many ways.
- For purposes of privacy, I am not mentioning the arms that my designer worked on. The examples for this post are taken from various major bishops and diocese around Texas.
- Ottfried Neubecker, Heraldry: Sources, Symbols and Meaning (New York: McGraw-Hill Book Company, 1976): 236-37.
- Ibid., 236.
- “About the Diocese,” Catholic Diocese of Dallas, https://www.cathdal.org/pages/about-the-diocese
- “About the Most Reverend Kevin J. Farrell, D.D.,” Catholic Diocese of Dallas, https://www.cathdal.org/pages/bishopkevinfarrell
- “Coat of Arms,” The Archdiocese of Galveston-Houston, http://www.archgh.org/about/Cardinal-DiNardo/Coat-of-Arms/