Secrets of the Axes

HOW TO GET THIS ARTIFACT SKIN: Wait. It's tied to a spawn timer inside the Oder Hall itself and it appears to just take some time to roll around. To date, it's been up every single day since the release of patch 7.1 and requires no artifact knowledge. It may require an internal trigger that we're not privy to, but, we've seen people as low as 107 get the hidden appearance. Just check with Helgar each day and see if he has something to say to you!

-Once you have the quest, leap down to Dalaran and High Overlord Saurfang will be waiting there for you. Speak to him then return to Skyhold.
-From there, speak to Helgar again and he'll send you over to the Ring of Trials (Directly across the Order Hall from Helgar)
-Hop in to the ring (+10 cool points if you use Heroic Leap) and High Overlord Saurfang will spawn to duel you
-After you defeat Saurfang walk off the edge of the ring to have a Valkyr take you out.
-Return to Helgar, follow the dialogue and you'll have a shiny new Axe!

********"And so it ends, not with a bang, but with a whimper." Thanks to everyone for their effort and time on hunting for this thing and all the great speculations! Maybe the next hidden appearance will be a little more lore and fun scavenger hunt styled. There were some great theories thrown around that I think everyone would have liked to turn out. *********

http://us.battle.net/forums/en/wow/topic/20750594885#post-1 -An official Blue post discussing hidden appearances.

Just tested on Live server, by resetting my artifact traits does not trigger this quest, so 39000 AP of mine just blown for nothing, but it is good to figure it out that this may not be the way to have the quest triggered for future references.

Just in case, I waited until my AK to reach Lv5, which helped me getting the Prot hidden skin, dont know yet if even higher AK lvl is required to trigger this quest

Anyway, the way of acquiring this quest remains unknown, hopefully other fellow warriors can shed more lights on this.

How I beat Saurfang as Arms:

Second Wind.

So the key is this: trigger Second Wind by chaining a Shockwave or Storm Bolt off things like his Earthshatter Shockwave. Let him cast about 3/4's of it, interrupt, and back off to bandage to supplement Second Wind.

(As it turns out Saurfang didn't spec into Trauma or Rend, so you're not going to end up with a DoT from his hits.)

This also works if you Pummel him instead during his Shout and immediately stun. You need 5 seconds for Second Wind to kick in; theoretically you could also extend your recovery time by activating Die By The Sword just as the stun is wearing off and recover over 60% of your hp.

Saurfang is also vulnerable to Intimidating Shout though I would have bet my transmogs on the iconic Horde Warrior raging through it. So again wait for a long cast, yell him into submission like Mrs. Saurfang, back off and bandage.

Beyond that Leap away from Bladestorm (or Die By The Sword if necessary) and pace yourself. Don't get caught in any of his big hits and he'll concede at 50% hp.

Remember your Mastery ability is Tactician; out think this hero instead of trying to overwhelm him. Patience and timing are the keys to the way of Arms, leave the raving and frothing for the Path of Fury.