In the workshop, faced with Chun's interested gaze, Reiger almost instantly stated the requirements he had already considered.
"I need a sword that is as durable as possible, not easily damaged, and ideally possessing an indestructible property."
Indestructible property.
As the name suggests, it refers to a property where the item is absolutely unbreakable and will never be destroyed.
Arms crafted by an Advanced Forger, who inherently possesses "forging" abilities, invariably come with various magic properties and effects. The indestructible property is one of these magic effects, considered relatively rare and high-level among special armament properties.
The sword used by Ais — "Sword of Despair" — had this first-tier armament with the indestructible property.