The nexus in Washington D.C. that Lara chose to destroy it was, according to Crane , an offshoot of the forge of Hephaestus, the blacksmith of the gods, to hammer out his mystic weapons. Jobe was able to retrieve the firearm before it was destroyed and gave it to Malcolm. Later, Malcolm attempted to shoot Diana Thomas , but Crane jumped in front of her and took the shot which transformed him into the Horseman of War.
The Turricula Ignis can be seen in a vision that Crane and Jenny experienced while trying to amplify Crane's lasting connection to the Avatar of War. It was in a box along with a near perfect replica. The Totem of War was used by Jeremy to shoot Crane in the vision while Crane shot Jeremy with the replica which resulted in a stalemate between them.
It can be assumed that it was hidden by Malcolm after Crane was transformed.