Currently to get the belts for joining investigation you need to talk with Usha again. This is a bit counter-intuitive as neither Eidein nor Lydia say anything about the reward at all.
In contrast, when joining preservation Eidein explicitly tells you to speak with Hanna who is also a rather relevant character unlike Usha who spawns only when needed.
Changing some dialogue for Eidein and Lydia, changing it so that Lydia gives you the belt or making Usha automatically approach you and start conversation (like she did the first time) would help new players find their reward.
