Hidden Potential of the Battlelord

To complete this achievement, you need to unlock one hidden appearance for your class. To be able to get a hidden appearance, you need to have the class hall unlocked and the base artifact for your spec.

Arms
[item=139578] is a reward from the Secrets of the Axes, which has a daily chance to spawn in the class hall.
To check if the quest is up, you need to speak with [npc=96586]. You NEED to talk with the NPC, because if the quest is up, there is no exclamation mark indicator. Also, if the quest is up, it is up for the entire region.
When you accept the quest, you will be asked to find the warrior with the axe - simply jump to Dalaran and speak with Saurfang at Krasus Landing. After that you will return back to class hall, to speak with them both, you will duel Saurfang, and at the end you will get the hidden appearance.

Fury
[item=139579] is unlocked by combining different parts. You must be exalted with Valarjar for the items to drop!
- [item=140660] drops from [npc=95675] in Halls of Valor (any difficulty)
- [item=140659] drops from Shar'thos (Broken Isles World Boss)
- [item=140658] drops from Nithogg (Broken Isles World Boss)
- [npc=114263] in Trial of Valor (any difficulty) can also drop the items needed
When you have all 3 items, simply combine them together.

Protection
[item=139580] has a daily chance to spawn in Neltharion's Vault.
First read [object=248979] tablet (in the class hall, right behind class hall upgrades NPC). Then go to /way #650 45, 73 (entrance)
Every day when you enter Neltharion's Vault, you have a chance to see the following message in the chat: "You hear a strange roar from the cavern ahead.". When you do, that means the hidden appearance spawned and now you just need to search the gold piles on the ground to find it and loot it.
If you do not get the message upon entering the Vault, try it another day.
Also, unlike the hidden skin for Arms, if the protection hidden skin is up, it is up for you and only for you.

malyasg, weapon equipped is never required. When it comes to specs, the answer is NO for arms and fury, YES for protection.

If the Arms variant is up Master Smith Helgar says "Your sword is incredible, I wonder if there is an axe to match it." when you approach him.