Each on the seven Trustees had one of the seven keys, until they were taken by Lord Arthur. The Keys are used to rule over the appropiate domain.
“The Seventh Key is paramount over all other Keys, and grants sovereign control over the The...Seventh Key
“The Third Key of the Architect that was wielded by Lady Wednesday (commonly known as "Drowned...Third Key
“The Sixth Key was held by Superior Saturday for over 10,000 years, until Lord Arthur claimed it...Sixth Key
“The Second Key of the Architect was the key held by Grim Tuesday, until it was claimed by Lord...Second Key
“The First Key was the key originally wielded by Mister Monday for 10,000 years, before it was...First Key
“The Fifth Key was originally wielded by Lady Friday for 10,000 years, before Lord Arthur claimed...Fifth Key