Galvoln

Galvoln (ガルヴォルン) was a magic metal from YGGDRASIL.

Description
In the Web Novel, the metal is a standard component to the maid outfits worn by the Pleiades. The skirt of the maid outfit possessed a magic black metal board over it, increasing its defensive properties. The board and even Yuri Alpha's chest-plate were made of the same materiel which was composed of three metals: magically enhanced steel, Adamask metal, and Galvoln.

Abilities
So far it is only described as a magic metal.

Trivia

 * In the Web Novel, the composition of the maid outfit is described however in the Light Novel its materials are omitted.