Once on the freighter search for a weapons locker next to a watertight door. Notice the control panel that opens the next door that is also in the same room. Equip the Dethex Launcher before operating the control panel. Jump and use its secondary function to place a guided grenade through the grate maze in the wall and floor of the room. Explode the grenade to open the locked watertight door. Inside is a weapon tech pick-up and a message that unlocks the trophy after it is read.