Niviculum
The word "Niviculum" is a combination of the Latin words "nix" for "snow" and "claviculum", for "small key". It is described as a piece of jewelry in the shape of a silver snow flake set with blue gemstones. The arms of the snowflake are shaped like skeleton keys.
The Niviculum was found by the Millwrights in Lycia's basket. A letter, supposedly written by her parents, asked them to keep it safe and give it to her when she was old enough.
The object is kept in a small box and is protected by a charm that prevents anyone from touching it.
The actual purpose of the Niviculum is as a general key for vaults protected by the Wintergale family. It can only be used by a member of the family, and only under certain conditions.