This sector houses the most dangerous criminals and preserves them for all eternity. It cannot be found in the Manual, because there can be no written record of it, as if someone found the Warehouse they could "debronze" the people who are imprisoned there. The people in The Bronze Sector aren't Hitlers or evil dictators, they were on there way to being them, but the Warehouse got to them first.
The preserving of people to prevent their evils being loosed upon the world (while also avoiding their death, which would impose evil upon the preservationist's soul) was a process first explored in Mesopotamia around 1250 B.C. The original process was too heavy and unsuccessful to be used. Today, the process used by the Warehouse involves flash-freezing bodies using cryogenics and preserving them further by bronzing.