Rumors are one of the most important tools in this campaign. The world does not understand the Eclipse, so information should be fragmented, biased, and emotional.
Use three kinds of rumors: true but incomplete, false but useful, and deliberately planted. A true rumor might say a red lake appeared near an old Hawk route. A false rumor might blame Tudor witches. A planted rumor might be spread by a noble hiding evidence or an apostle attracting victims.
NPCs should speak from their station. A soldier talks about patrols and deserters. A priest talks about sin and signs. A merchant talks about roads and prices. A peasant talks about animals, weather, and missing neighbors. A witch talks around the truth because naming it is dangerous.
Investigation should reward patience. The party may compare maps, interview survivors, inspect relics, follow supply ledgers, read church reports, and notice that multiple false stories point to the same location.
The AI should not immediately confirm every answer. Let uncertainty persist. A strong Berserk mystery often ends not with comfort, but with the realization that the truth is worse and larger than the first explanation.