Complex sentence: The City of London swords are five ceremonial swords owned by the City of London, namely the Mourning (or Black) Sword, the Pearl Sword, the State (or Sunday) Sword, the Old Bailey Sword and the Mansion House Justice Room Sword.
Split into simpler sentences: The City of London swords are five ceremonial swords owned by the City of London. The five City of London swords are the Mourning Sword (or Black Sword), Pearl Sword, the State Sword (or Sunday Sword), the Old Bailey Sword and Mansion House Justice Room Sword.