Hammer of the Emperor introduces the idea of Variant Equipment patterns. You take a standard piece of gear, and acquire it in such a large quantity that the design has a few positive and negative variations based off of the "default" pattern which gives them unique bonuses or penalties.
My players love the Merovech Assault Lasgun, and have probably acquired well over 100,000 of them by this point to hand out to their trained troops, or to arm enemies against themselves. Then they started making them on one of their Forge moons, so we decided to roll up a variant pattern and name it the "Hos-Pattern Merovech Lasgun".