The term “red weapon” was derived from the deep red projectiles that they fire, unlike any other type of weapon. During the Destroyer War, the Lorgans and Gumai were desperate and tried to hide on the water world of Ju. They found an ancient ruin containing a relic called the Book of Knowledge. This object contained the necessary knowledge to build weapons that could even penetrate the synthium skin of the Hazkan.
Since the Gumai hid the book after the Destroyer War in order to minimize the danger it posed, no more of these weapons were created. However, the remaining copies made life difficult for the Initiative as the Lorgan War progressed. Nobody, not even Kalohi and Holon, understood how these weapons worked. Therefore, Amaru Khan used many resources to find the book.
During the space battle above Earth, Nina Chevon managed to convert the Renegade’s main cannon so that Carter’s pistol could turn it into a red weapon once before it was destroyed.