It is unknown how this clue was hidden originally but it was placed inside a box that had five artifacts that needed to be placed into small slots in the box for it to open. There was a jade necklace that had a dragon carved onto it that represented the Ekaterina branch. The necklace was owned by Grace Cahill but it was passed onto Amy Cahill after her death. The bear claw, from a cave in the Bahamas, represented the Tomas, the wolf fang, from Isabel Kabra's charm necklace, represented the Janus, and the silver snake earrings, one held by a woman in Jamaica and another by Nellie Gomez, symbolized the Lucians. Unknown to the other clue hunters, there was a fifth slot that was extremely hard to see. Eventually the slot was found but it took a while. The slot held a gold mobius strip that was placed in the statue of Nanny of the Maroons. It represented the Madrigals and how they are trying to bind the Cahill family together.
Mace is actually a type of spice. It has been used for defensive purposes as it can cause a burning feeling when in contact with the skin. It is typically put in bottles and used to spray into the eyes of one's enemies.