Erebus
Ranged · Submachine Gun · Power · Unique model (Militech Erebus)
This one sits behind a choice
Firestarter: Reed. Decide before the quest closes, because the other side of that choice locks this weapon away on this save.
What it does
Where it sits
What you need
Pick it up before
If you miss it
Who it suits
The route
Show the step by step (spoilers)
Reed's route, during Somewhat Damaged. The crafting spec sits in a locked bunker room near the Victor dataterminal, and the wall circuit breaker nearby gets you in. Loot the Cerberus Behavioral System Component off the robot chasing you as well. After Phantom Liberty, take the component to the Kabuki Market netrunner and choose Erebus when the unique reward comes up.
Confirmed by published guides, not yet by Vaexil. Nobody here has walked this one in game, so take it as a strong lead rather than a promise. Cross-checked against CD PROJEKT RED patch notes, VULKK, and the Cyberpunk Wiki, for patch 2.31 with Phantom Liberty.