- Main article: Ishmelga
The Erebonian Curse originated from Ishmelga, which spread malice throughout Erebonia in the form of a curse in order to become a god-like entity with absolute power as much as possible. The curse preys on those with insecurities or specific hatreds.
The curse was fairly weak, having had no prominence during the first two Cold Steel games, but began to slowly manifest in the series' third game. At the end of said game, in Trails of Cold Steel III, Finale: "For Whom the Bell Tolls", the Great Twilight was initiated through Giliath Osborne's ability to unify with the curse, further spreading the curse across Erebonia and its territories. Despite this, Emperor Eugent Reise Arnor III believes it to have been responsible for certain tragic incidents throughout the history of Erebonia, including the fighting that resulted in the War of the Lions, as well as the Hamel Tragedy.
The curse not only affects people's thought, it also affects their fighting abilities.
For example, the Knights of Blood and Iron (Rufus Albarea, Lechter Arundel, Claire Rieveldt, and later Cedric Reise Arnor), the Imperial Defense Force, and Alan have demonstrated increased fighting capabilities. Persons influenced by the curse have their eyes marked by some sort of crest and a black, malevolent aura surrounding them.
Another effect of the curse is forcing selected people into specific roles. This 'compelling force of the curse' has robbed many Erebonians of their fate throughout history. One such victim is Ash Carbide, who was forced by the curse to pursue the instigator of the Hamel Tragedy which culminated in his attempted assassination of Emperor Reise Arnor III.
Victims of the curse include, but are not limited to:
- A group of nobles poisoned by the influence of the curse allowed Georg Weissmann to manipulate them into hiring a group of jaeger dropouts to attack the village of Hamel and frame Liberl for the massacre, resulting in the Hamel Tragedy and subsequently the Hundred Days War.
- Rean Schwarzer has been a candidate for the curse ever since Giliath Osborne's heart was transplanted into his body. The curse's influence led to him triggering the Great Twilight and was later used as a spare when Osborne died. At one point, he nearly succumbed to the curse out of sheer rage at the misery Ishmelga had caused.
- Ash Carbide was regarded as a Calvard spy who tried to assassinate the emperor, fueling nation-wide animosity toward Calvard. The curse amplified the hidden trauma of the Hamel disaster, and since he didn't have a clear target to blame (he didn't know who had been behind the Hamel disaster), his hate targeted both Osborne and the emperor, both potential candidates for having been behind the attack.
- Victor S. Arseid was used by the curse as Erebonia's strongest swordsman and given the role to rise the curtain for the Third Rivalry by fighting Class VII.
- Arthur, Elsa's former boyfriend. Due to his family rejecting and threatening Elsa, she committed suicide and he was subsequently disowned by his family. Guilty for being responsible for her death, the curse amplified these feelings and he attempted to make nobility pay by covertly seizing assets, leaving them on the verge of bankruptcy. He is returned to his senses by Elsa's uncle and cousin, Carl and Machias Regnitz.
- Wads, an employee of Kleist & Co., became so consumed by ambition that he completely lost sight of morality, scamming the inhabitants of Parm out of family heirlooms just to increase company profits. After he exploited Mayor Mathim's consumption by the curse to trick him into abandoning Alster so he could raze it to the ground for a new factory, Hugo Kleist was forced to suspend him indefinitely as he was hurting innocent people and had become a public relations nightmare for the company.
- Alan, a model Erebonian soldier prior to the Great Twilight, became consumed with fear of being unable to protect Bridget, resulting in him becoming psychotically and fascistically obsessed with serving Erebonia and crushing Calvard, at one point berating two men for being relieved not to have been drafted yet. His fellow Thors alumni, Bridget included, brought him to his senses prior to the end of the Great Twilight.
- Ron and Morris, Elliot's former music members. The two young men were jealous of Elliot's quick rise to fame and Kalinka for working at the Rieveldt Company. The curse took advantage of this jealousy, making them compose marital music that induced aggression in listeners to help participate in the war against Calvard. They are soon returned to their senses by Elliot and Kalinka.
- Miguel, an informant based in Raquel. The curse's influence causes him to seek even shadier deals. He is eventually brought to his senses by Ash Carbide, whom he rescued from the Hamel Tragedy when he was a young boy.
- Mayor Mathim of Alster, devastated by Olivert Reise Arnor's supposed death, became obsessed with contributing to the war effort, to the point of trying to abandon Alster for a nearby mining village. Mathim comes to his senses after he realizes just how far Wads was willing to go and later is deeply repentant for his actions. His heart is calmed when Olivert himself later pays a visit to the village.
- Black Alberich exploited Cedric Reise Arnor's inferiority complex to corrupt him after he was forced to awaken Testa-Rossa, leading to his personality taking a turn for the worse and him becoming a fanatical supporter of Chancellor Osborne. Initially, this was limited to mere arrogance, but in the aftermath of Ash shooting Emperor Eugent, he gladly took part in the effort to unleash the Great Twilight, going as far as to attempt to murder Altina Orion to create the Sword of the End. He only grew worse during the Great Twilight; as an example, he attacked the Pantagruel with the intent of framing Calvard for the attack, which an outraged Joshua Bright explicitly compared to the Hamel Tragedy. He regained his senses when he realized he would have to fight Osborne were he to reach the Sixth Rivalry, but overwhelmed with guilt at his actions and realizing he would likely be disinherited, once the Great Twilight was over, he decided to join Ouroboros.
- Coppe, a cat loosely affiliated with the Special Support Section, turns vicious for a time under the curse's influence.
- Mimi is a young girl who looks up to the members of the Special Support Section and who has been caring for Coppe in their absence. For a time, however, following the advent of the curse, she can no longer even remember their names or if they ever even existed at all. As they become active again in Crossbell, she begins to recover her memories.
- Cain, a resident of the village of Leeves. He chastises Rean and the students of Class VII as a disgrace to the Empire and the residents of the village by extension for supporting them. He states that they should all be thrown in jail, "just like those Calvardian spies."
- This curse does not actually take control of people, but instead it could be considered similar in effect to a psychedelic drug, in that it erases mental inhibition and causes people to become obsessed on thoughts, memories and emotions they normally keep hidden and don't show on the outside. It's not known whether or not the curse actually gives people power, or simply allows them to manifest the part of their innate power that they normally cannot control.
- Following the advent of the Great Twilight, those with certain training or innate abilities are able to sense the presence of curse as a black wind or aura surrounding a person.
- Sen no Kiseki Magazine, Volume 5: "Beyond the Truth" (p. 37)
- Sen no Kiseki Magazine, Volume 5: "Beyond the Truth" (p. 38)
- Trails of Cold Steel III, Chapter 4: "Radiant Heimdallr" (07/17)