Reductor Pistol
With the arrival of Roboute Guilliman and the beginning of the Indomitus Crusade, Primaris Apothecaries started to carry an enhanced version of a Reductor that can also double as a close ranged weapon known as a Reductor Pistol. The Reductor Pistol is similar to the Narthecium's Reductor tool but takes the form of a pistol and is used to both quickly retrieve and store multiple-sets of Astartes gene-seed on the battlefield. The Reductor is designed to punch through Space Marine Power Armour quickly and cleanly; and can do much the same to the skull of a rampaging Ork Warboss if he gets close enough to the Primaris Apothecary.
The invention of the Reductor Pistol is due to the simple problem of flexibility. You see, a normal Reductor for those who don't know, is a special medical tool used by Apothecaries as a way to safely retrieve the crucial gene-seed of their fallen Battle-Brothers so that new Astartes might be raised from among their Chapter's Aspirants. Retrieval and storage of a fallen Battle-Brother's gene-seed is so critical that Apothecaries carry a special tool for this operation, often included as part of the Narthecium. While a Reductor is not required for Progenoid removal, it significantly reduces the time. This surgical implement fastens under the wrist. It includes a monomolecular saw for penetrating Power Armour and Ossmodula-enhanced rib cages, and a diamantine-tipped extractor drill.
While this may sound useful and it is, the point of contention is that having a piece of medical equipment permanently attached to your power armor could risk it being damaged in the heat of combat due to some numbskull trying to go all CQC on the Apothecary. So having the Reductor separate and actually become a weapon of sorts could provide the Apothecary a way to safely place this important tool somewhere where it won't get smashed. Plus, in combat, a pistol is much more easier to handle than a wrist mounted tool that is barely able to perform efficiently in the heat of battle.