Theresia van Astrea

Theresia van Astrea (テレシア・ヴァン・アストレア) was the former Sword Saint and Wilhelm van Astrea's wife and the hero of civil war 40 years prior to the main story. She went missing while fighting the White Whale 14 years ago, but was later seen as a zombie fighting for the Witch Cult. At the end of Arc 5, she was successfully killed by her grandson, Reinhard van Astrea.

Appearance
She was tall and had long red hair with flowers attached to it, blue eyes and a white complexion. She used to wear a white dress when operating as a knight of the Royal Guard, while in her free time she wore a green and white dress

Personality
Theresia was described as an open-minded sociable person who had a fatal flaw of shoving aside her own personal feelings while only focusing on that of others. Despite her immense talent and lineage she never wanted to be a swordsman and take up the mantle of the "Sword Saint". However, certain circumstances forced her to resign to her fate in order to end the civil war and protect the love ones she had left. This eventually led Wilhelm to "take" the sword from her and free her from a life of bondage by duty. Theresia was avid flower lover and could be found viewing them in ruins where she and Wilhelm routinely met in her spare time.

Past
Theresia was born to her father Veltol Astrea, and her mother, Tishua Astrea. Since she was born with a Divine Protection, she refused to use a sword, fearing hurting others. However, at the age twelve she obtained the powers of the Sword Saint from her uncle Fribal van Astrea. During the Demi-Human War, her uncle, including her brothers, died participating in battles. Later, Theresia found a ruin, where she saw Wilhelm train. In each encounter, she asked him his reason for using the sword, to which he answered that it was what he had, but later he changed it saying that he used it to protect others. Eventually, Theresia was informed of Wilhelm's achievements in the war and congratulated him.

One day, Wilhelm mentioned that the Demi-Humans were going to attack his home. She accompanied him to his village, and at the last moment saved him from being killed, defeating everyone before the reinforcements arrived. When he recovered, Wilhelm confronted her for hiding the truth from her powers. As he confronted her, she easily defeated him, before stating that he would not return. Since she had to protect him, he decided to participate and end the Demi-Human War. In gratitude a ceremony was made, nevertheless, a hooded man appeared, who defeated her in a duel. The person revealed to be Wilhelm, recovering his responsibility to use the sword for being weaker than her, and they share their first kiss.

The happy couple got married and eventually formed a family, having a son, Heinkel Astrea, and eventually a grandson, Reinhard van Astrea. Later, everyone was informed that the Hakugei was approaching. Since Wilhelm was engaged in another mission, Theresia took the place of a fearful Heinkel to lead a group of knights to defeat the Demon Beast, whose attack was orchestrated by Pandora. However, during the battle, she lost her powers as Saint of the Sword, and passed away.

Arc 5
Many years later, Theresia was somehow resurrected by the Witch Cult. Eventually, when the Witch Cult arrived in Priestella, the Sin Archbishops took control of the city, Thearesia was also part of this, however, Subaru organized a plan with his friends to defeat them. Suddenly, she fought against Wilhelm, only to be quickly defeated, but she soon counterattacked, then noticed Heinkel as her next victim, but Reinhard interposed. Because he considered her a defiled corpse, he defeated her mercilessly with a blow. Already on the ground, Theresia recovered the reason in the arms of Wilhelm, moment in which they confessed their love, and while she turned to ashes, she mentioned how happy she would be if he reconciled with Reinhard.

Abilities
Divine Protection (加護 Kago): As the Sword Saint, Theresia had the Divine Protection of the Sword Saint, however she was born with the Divine Protection of Grim Reaper (死神の加護 Shinigami no Kago). Slashes imbued with the Divine Protection's power leave wounds that are unable to be healed. The power of the Divine Protection increases the closer she is to the target, and she can even reopen wounds others have if they are close enough and were originally inflicted by her.
 * Sword Saint (剣聖 Kensei): Theresia became the Sword Saint when she was 12 years old.

Master Swordsman: Theresia was highly skilled at using the sword. Contrast to Wilhelm's deftier and measured style, her swordplay is more momentum based, employing a lot acrobatic flushes. It's described as if she is doing a beautiful deadly dance.

Equipment: As the Sword Saint, Theresia wields the Dragon Sword Reid (龍剣レイド Ryuuken Reido). The sword can only be drawn against opponents it deems worthy for it to be used against. She also wielded the Holy Sword Astrea (聖剣アストレア Seiken Asutorea), her favorite sword, which was later inherited by her son, Heinkel Astrea.

Trivia

 * Theresia was born on the June 12, Lovers day.