Supposedly there is a Dark Justiciar helm in the blighted village on a skeleton that also makes Shadowheart react. I haven't been able to find it, but I have seen a few mention it. This is not the scene behind the windmill. It's another one.
You can find it by entering the Blighted Village from the entrance facing the direction of the Grove and going right between the building and village wall until you reach the end of the buildings. The corpse should be next to the last building there. The shape match the representation of the defeated Shar followers on the Grove's mural.
Hmm...I appreciate it, I found it, but didn't get any sort of reaction from her. I had found it in one of my previous playthroughs as well, and no reaction there either. Must be bugged for me.
She only react to the first thing you find in the village among:
- journal talking about the kidnapped kids
- the helmet
- the broken Selûne statue behind the windmill
Could be another one, but I don't remember it right now.
It could also be bugged for you. I saw someone who had the powerful stone on the pedestal, while in all 3 of my PT, it was on the ground.