It's possible I'm missing some nuance in a quick glance in my own code, but I think that both wood and dragonscale are mostly okay.

Each of your light warpriest benefits cares about one of two things:

1) How many pieces of heavy armor (by material) you're wearing, and I want to say stone, bone, and metal are your generally dangerous materials here, and

2) The total weight of the armor you're wearing.

All of this being on a sliding scale.