Grey Maiden Plate

[ebfi3e]

Do the paladin/fighter boosts to heavy armor proficieny work with Grey Maiden Plate?

Also, considering how bad regular plate is, isn't Grey Maiden Plate worse?

[Lavieh]

Given the wording on the Grey Maiden Archetype, you need to gain its proficiency through feats. If you invest three feats in the plate, it actually doesn't look too bad - only at the cost of three feats.

[ebfi3e]

Plate sucks in general. There are a few threads about it. Additionally, while the simplest way to get into Grey Maiden is through fighter or paladin, it is not required. One could take fighter archetype or armor training general feat instead.

My point is that if Grey Maiden Plate requires the character to take feats to keep it as good as regular plate then it is even worse than plate.

[Cantriped]

Grey Maiden Plate is still Heavy Armor, so fighter/paladin proficiencies apply normally if you find a suit of it. The Grey Maiden Archetype is otherwise required for "access" though, and grants proficiency with that armor specifically (not heavy armor in general).