“To me, Argreion!”
— Arianrhod, summoning Argreion
Arianrhod, still known as Lianne Sandlot when she took on the trial to become Argreion's Awakener, has been its Awakener since S.942. Roselia guided her through the trial. Initially Sandlot considered its power too great for mankind to use and kept it sealed in Lohengrin Castle. Toward the conclusion of the War of the Lions, however, she changed her mind. She summoned Argreion to fight alongside Dreichels Reise Arnor, Awakener of Valimar, the Ashen Deus-Excellion, against the Vermillion Apocalypse. They were victorious, but Sandlot was mortally wounded and soon thereafter succumbed to these wounds. Half a year later, she revived in Elin where Roselia had brought her.
Argreion first appears in Trails of Cold Steel III, when Arianrhod summon it to destroy the remains of the Aion Type-α II. Its existence has been foreshadowing since Trails of Cold Steel II, however, where Celine informs the protagonists that the Divine Knight that once rested in Lohengrin Castle was recently removed.
Like Arianrhod herself, Argreion wields an enormous lance.
After being defeated by the Ashen and Azure knights, Argreion was destroyed by Rufus Albarea and his Divine Knight, El-Prado, causing Argreion to be absorbed into it. Argreion being absorbed by another Divine Knight nullified the Immortality of Arianrhod and led to her death.