Note: You must beat the game once in order for secrets to appear.
Arc Charger: No Way Out -- Follow the hallway down to the officer's quarters.
Backlash Grenade: The Cathedral -- Upon entering the house, take the first door on the left.
L11-2 Dragon: Evacuation -- At the end of the Radial Mine path, enter the small bunker.
Reapers: The Gauntlet -- Ent...