Exhausting the power of one's stigma is potentially life-threatening to the host.
Every Dominion, a special rank among the Gralsritter of the Septian Church, experienced the stigmatisation. There have never been more than twelve Dominion at a given time in history, meaning that there have never been more than twelve manifested Stigmata at the same time. Dominions can sense potential stigmatisations, as Ein Selnate displayed with both the stigmatisation of Kevin Graham and Wazy Hemisphere.
As a Dominion becomes more skilled at drawing power from their stigma, their attacks become stronger and they develop new abilities. The hypothesis that Kevin could have developed the ability to read his support Ries Argent's mind is denied by neither. It is also believed that Ein owes her position as first Dominion because she is most skilled at extracting her stigma's power.
It appears two conditions have to be met for a stigma to manifest. First, the host needs to be mentally burdened, which usually comes in the form of a trauma. Second, the host needs to be in the vicinity of an artifact.
The stigmatisation of Kevin suggests that stigmata can manifest partially when not in the vicinity of an artifact. In Trails in the Sky The 3rd, Kevin theorised that he survived his mother's attempt to strangle him because of his semi-manifested stigma.
Dominions are capable of channelling the power of their stigma through their Merkabah aircraft. During the Finale of Ao no Kiseki, Kevin Graham has Squire Marcus activate the "S Mode", in which S stands for stigma. The blast was powerful enough to take out the airspace patrolling Aion Type-β.
Georg Weissmann experimented with reproducing stigma on normal humans to create an army of superhumans (
The artificial creation of Stigmas is highly looked down on by the Church; upon verifying Weissmann's stigma experiments, he was promptly excommunicated from the Church. Despite being excommunicated, Weissmann continued to experiment with stigmas, which resulted in Kevin being sent by the Church to assassinate Weissmann to stop the production of such stigmas.
During the events of Trails in the Sky SC, Kevin used some hypnotic practices to help Joshua weaken the Stigma's hold on him, coupled with his prodding of the Stigma when he realized what it could do to him. With his adoptive father's assistance, who told him to create a trigger that would destroy it in an undisclosed letter, Joshua was able to break Weissmann's control over him.