Seraph

The Seraph is the key to unlocking the Catacombs of the Talion at Barkhang Monastery in Tibet.

Leader of the Fiamma Nera, Gianni Bartoli, had somehow got hold of the Seraph and was travelling with it on his ship, the Maria Doria, when Father Barkhang bombed the ship. Gianni died and the Seraph was lost in the ocean.