The iron knife (initially wielded by Treila in hope of killing Voyne) plays a key role in the plot: Unlike other iron objects (which repel magical figures) it grants immunity to iron. When the Lady or the saints possess it, they can no longer be harmed by iron and can pass freely into spaces where iron objects reside. The iron knife symbolizes how power is dynamic and fluid, and how vulnerability and strength are two sides of the same coin. The knife renders the Lady immune to the very substance it is fashioned out of, and possessing the knife grants her greater strength (although it might plausibly be expected to weaken her). When the knife is stuck in Voyne’s throat, it initially appears that only Phosyne will be able to remove it but Treila is the one who actually pulls it out. Who has power, and what kind of power they hold, is unpredictable and ever shifting. The knife’s initial connection to Treila’s revenge quest furthers this symbolism: She claims to be insistent on killing Voyne, but whenever she encounters the knight, Treila becomes overwhelmed by complex and ambivalent emotions.

The knife as a symbol of circulating power is affirmed when the Absolving Saint brings it to the three protagonists and offers it in exchange for leaving the castle. The Absolving Saint voluntarily offers to relinquish a talisman that would afford him greater power because he no longer wants it. He concedes defeat and brokers the terms of surrender, showing that the forces of magic are no longer the ones setting the terms. This final surrender of the knife symbolizes how power dynamics are always fluid, and who is in control is not always truly apparent.