One of the three Mortal Instruments given by the angel Raziel to Jonathan (the first Shadowhunter and Jace’s namesake), the adamas Mortal Sword is described by Jace as a “dark, heavy silver, glimmering with a dull sheen” (242). Light moves across the blade of the Sword as if the Sword is lit from within. The Sword, which is also called Maellartach and the Soul-Sword, has a dual role in the narrative, functioning as both motif and symbol. As a motif, it illustrates the important theme of The Complicated Battle Between Good and Evil. The novel argues that the boundaries between right and wrong can be shifty and treacherous. Further, evil can be as self-righteous as good, invoking noble ideals to justify its agenda.

Similarly, the Sword, as a hallowed and angelic object, is meant to do good and judge the truth, but Valentine seizes it to convert it into an evil instrument. This shows that the Sword is a mere weapon: Who wields it and why is more important. By the time Jace holds the Sword in the demon ship, Valentine has already dowsed it twice in the blood of a Downworlder child. The Sword’s allegiance is shifting, so Jace can see the demons it has attracted to the edge of their world.