So I looked at the Ghost Eater archetype which seems interesting but one issue with it is that there are quite limited opponents to use it against.
Ghost or undead enemies:
In Book 1 you have the Temple of Irori (but you gain the archetype after clearing this), and the Watchtower Ghosts.
In Book 2 you have the Jiang-Shi.
In Book 3 there isn't anything.
So I was thinking of how to make this archetype more relevant:
1: Give access to it before the temple, probably instead of giving the ghost touch runes.
2. In Book 2 make Grandfather Mantis incorpereal (possibly just adding weakness to ghost touch among the weakness to force and positive).
3. The tournament is called The Hungry Ghost tournament but in one encounter he summons a troop of non-undead corpereal spirits which the archetype doesn't interact with at all. I'm not entirely sure how to make a ghost troop but I think here is also a good place to make it relevant again. Possibly changing other encounters to ghosts since it is called the ghost tournament.
If you have ghosts or undead I missed or other ideas or feedback I'll gladly accept it.