|“||The Soul-Sword reveals all.||”|
The sword's primary purpose is to compel the truth out of a person. Its truth-drawing powers can be painful, particularly when the person being interrogated with the sword struggles or hesitates to give an answer and will continue to hurt until the person gives an answer, as if the sword pulls and forces the truth out from them.
The Sword is also present during Nephilim trials, during which people involved or set to give statements are asked to hold the sword and swear to tell to truth. Every time it is used, a Silent Brother is present to handle the sword. It can also be safely used on Downworlders.
The Soul-Sword can also be used to allow a Shadowhunter to recover his/her own memories, especially blocked ones. It has its limits, as it would be unable to retrieve memories taken from the individual. The Soul-Sword is held, dangling, above the person's head and the truth is "carved" from his/her mind. This process can kill a person not strong enough to withstand its power.
The Sword can also have a dark purpose. By design, the sword's secondary purpose can be activated with angelic energy—by the touch of someone with pure angel blood, like an angel or someone like Clary Fairchild. When wielded by someone with angel blood and struck with a bolt of lightning, the sword would release heavenly light that would destroy all demon-blooded creatures, namely demons and Downworlders, in its path. According to Sister Cleophas, it would be impossible to turn off once activated.
In 2016, Clary went to the City of Bones to let the Brothers use the Sword to access her blocked memories. It worked to an extent, but most of her taken memories remained lost. The Sword was later used for the trial of Isabelle Lightwood at the New York Institute, overseen by Inquisitor Herondale and Brother Jeremiah.
Some weeks after, the Sword was used to question Jace, this time overseen by the Clave representative Victor Aldertree. Later that evening, the Sword was stolen by Valentine Morgenstern, who intended to activate it to decimate the Downworlders. The Silent Brothers protected the sword with their life, especially Brother Jeremiah, who held onto and refused to let go of the sword until his death.
Though its purpose used to not be common knowledge and a well-kept secret, known only by a select number of individuals, including or exclusively the Iron Sisters, it became known by other Shadowhunters after Isabelle and Clary asked the Sisters, and the news spread among the Downworld after Maia Roberts overheard the conversation about it at Magnus's apartment.
Led to believe that the Sword can be destroyed under the touch of a Morgenstern with demon blood, Jace sought to touch the Sword, not yet knowing that he in fact had angel blood and thus accidentally activated the Sword. Valentine wielded the sword and killed several Downworlders inside the Institute, the sword's effect contained by the adamas in the Institute's walls. With the immediate threat that the Sword could be used to kill all Downworlders, Clary received a vision of a rune from Ithuriel, and before Valentine could use the Sword outside to kill all Downworlders and demons, Clary drew the rune on the surface of the sword, rendering its dark power useless. Before they could secure the sword, Jonathan Morgenstern stole the Sword, and the Clave tried to hide the fact that the Sword was missing from the Downworld.
- ↑ 1.0 1.1 2x05: Dust and Shadows
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2x06: Iron Sisters
- ↑ 3.0 3.1 3.2 3.3 2x04: Day of Wrath
- ↑ Writer Jamie Gorenberg breaks down the episode — Shadowhunters on Freeform
- ↑ 5.0 5.1 5.2 1x11: Blood Calls To Blood
- ↑ 6.0 6.1 2x02: The Descent Into Hell Isn't Easy
- ↑ 2x07: How Are Thou Fallen
- ↑ 2x10: By the Light of Dawn
- ↑ 2x16: Day of Atonement
- ↑ 2x20: Beside Still Water