By the time you enter Nefarious's space station to fulfill Captain Quark's plan to destroy the Armada, you should have purchased most of the weapons by that point. Entering the space ship should allow you to access the Rift Inducer weapon, which is the last one you will need for this trophy. Once you purchase all weapons ending with that, and the only thing available to purchase from then on is Full Ammo, your trophy should be flagged to chime up.