The Red Death was originally made as a cheaper version of the Suros Regime. However, thanks to the use of synthetic smartmatter, the wielder of this prototype went insane, and slaughtered many a Guardian. This is the reason behind the skulls and other dark tones on the Red Death

Thank you for this I never new that I always believed the red death was just a standard auto rifle who had many owners and each owner would add something to it one owner was a fallen who took it from a guardians body and used it for a time and I believe after the fallen had it someone made it so it fired in 5 round sequences this is the red death we know now