The word “sudarium” means “veil” in Latin. This veil makes an appearance in ecclesiastical heraldry in the coats of arms for abbots (see the arms of Abbot Gregory Duerr, OSB of Mt. Angel Abbey above). Since 1969 and the Papal Instruction, “Ut Sive” the use of the mitre and crozier in the coats of arms of Cardinals, Archbishops and Bishops has been discontinued. However, the mitre is still used in corporate arms for abbeys and dioceses. Similarly, the crozier is frequently used as an ornament to ensign the shield of an abbey. In some countries the mitre is still erroneously used by bishops to ensign their arms alone. While that was commonplace in the Middle Ages it is really incorrect (mind you not “unallowed” but merely “incorrect”) in modern heraldry.
While Pope Paul’s Instruction asked that the mitre and crozier be omitted from the arms of Cardinals, Archbishops and Bishops as unnecessary due to the fact that the galero with its colors and tassels and the (arch)episcopal cross are sufficient emblems for those prelates the crozier has been maintained as the external emblem particular to the arms of abbots, along with the sudarium, and of abbesses. However, to mark the crozier as the emblem of a monastic prelate it must have the sudarium attached to it.
The reason for the sudarium started out as a practical one and has, like so many other heraldic emblems, evolved into something merely symbolic. At the time when abbots were conceded the privilege of using pontifical insignia (i.e. mitre, crozier, ring) they were not originally allowed to wear pontifical gloves. The veil was attached to the crozier in order to protect the staff of the crozier from dirt and perspiration on the hands of the one holding it. Later, pontifical gloves were also conceded to abbots (and abbesses) so the sudarium became more symbolic than practical. It is also possible to find frequent examples of abbatial arms that have a crozier without the sudarium or, even, to omit the crozier entirely. This is quite incorrect.
The external ornaments proper to an prelate with the rank of abbot are the black galero with twelve tassels and the crozier placed behind the shield with the sudarium attached. Occasionally, it is possible to find the sudarium still actually used by some abbots, such as those at Heiligenkreuz in Austria. (below)