Mithril Full Plate on Barbarian

[Atalius]

Can a Barbarian who doesn't have the heavy armor proficiency wear Mithril Full Plate armor? And if so, are there any penalties to it?

[TriOmegaZero]

Yes, but he takes any remaining Armor Check Penalty as a penalty to all of his Str and Dex based checks.

Nonproficient with Armor Worn wrote:

A character who wears armor and/or uses a shield with which he is not proficient takes the armor's (and/or shield's) armor check penalty on attack rolls as well as on all Dexterity- and Strength-based ability and skill checks. The penalty for nonproficiency with armor stacks with the penalty for shields.

Full plate has a -6 ACP and mithral reduces that by 3. So he would take a -3 to all attacks, all Str and Dex checks, all Str and Dex based skills like Climb and Acrobatics, as well as initiative due to it being a Dex check.

[Chess Pwn]

Yes, anyone can wear that.
A barb would get the ACP to all of his str and dex d20 rolls and not just skills. So initiative and attack rolls.

[graystone]

You could take the Serpent Runner, Armor Expert and Sargavan Guard traits. Each lowers your ACP by 1 so all three means no penalty when applied to mithral plate. There is also the Nimble armor mod, Comfort enchant and other things that reduce your ACP.

[Chris Ballard]

It still counts as heavy armor for proficiency and as medium armor for everything else.

[Atalius]

Thank you. Not sure why it posted a duplicate of my question , sorry.

[Lady-J]

celestial armor on the other hand counts as medium for proficiency