Slayerite

Harvested from the fierce Slayer Crab, slayerite is both chitin and metal made from a collection of plate armor and weapons of those the beast has slain. Depending on the quality of the foes it has faced and the quality of metals used, the material could become more sturdy or more brittle, and even keep the properties of the metals used, such as the magic nullifying qualities of Avalicite. This however has led to an inconsistent quality of the metal. There have been disastrous attempts to cultivate slayerite in the past, thus its rarity easily justifies its high price.

Alexandra Athana's armor is a hodgepodge of alloys and materials, but most notable of all it's mostly composed of slayerite. There are rumors of her having tamed a slayer crab somehow.