For those who have not completed games in the Xenoblade Chronicles series, this page contains spoilers regarding the plot. Discretion is advised.
Gadolt's Cannon were weapons designed for Xenoblade Chronicles. They were rifles to be wielded by Sharla, however for unknown reasons, they were cut from the final game. It was most likely intended to be dropped by Gadolt after he is fought as Jade Face in Mechonis Field along with Gadolt's Gun Turret.