You allow Ciandra, Arcanum Alchemist to examine your Repaired Shadow Stone.
Ciandra, Arcanum Alchemist tells you, "I've found a way to alter these stones to work with an Isparian Weapon, but I need you to get something for me first. I've managed, in my research, to locate a possible location for one of Atlan's Workshops, where he made the first weapons we based the Isparian Weapons on."
Ciandra, Arcanum Alchemist tells you, "The portal should be at 66.9N 15.9E, along the outside of the Mt. Esper Caldera. Go there, and gather for me whatever information you can."