The article directs people to Book of Ruin - the profile shown shows two guns and this fellow has one and one claw thing.
The
Book of Ruin Heretek is an Outlaws-only Hanger On, who has
one gun (you choose between either a Grav Gun or a Plasma Gun), and the Munitioneer skill, but like most Hangers-On, never shows up on the table unless you are fighting with Home Turf Advantage as the Defender in a scenario. No melee weapons at all.
What you really get is a special rule hidden in its descriptive text and not as a listed Special Rule at all (which makes one question the existence of editors, but also question whether it would keep that ability if elevated to Outcasts Gang Leader, or really even just in the rules themselves, though intent is clear).
That ability allows them to once per scenario temporarily give a weapon Blaze, or Rad-Phage, or Shock, or Power, or Concussion. If it is a shooting weapon, then it also gains Unstable. If it is a Melee or Versatile weapon, then it also gains Reckless.
If it is a Blunderpole, presumably it gets both Reckless AND Unstable.
Since the Heretek will rarely see the table, the main purpose of that 40 credits is to give Blaze, say, or Rad-Phage, to some melee weapon. It does happen after Crew selection, so it has more flexibility to ensure it has an on-table effect than, say, spending 40 credits to just upgrade some specific weapon. Or perhaps the writers underestimate how unforgiving Unstable is as a weapon trait.
Anyhow. Rather than the powered melee weapon, a better choice for the sculpt would have been tinkering tools, allowing the surgically added gun-servitor to take care of the combat role. As a resin mini, changing out even just thr prongs on that melee fist seems likely to be fraught, to me.