Bindings of the Windlord

Here is everything I know about this artifact appearance so far:

1. The bindings CAN drop from M+ chests (I got the right one from a +2 VoW chest).

2. You need to have found at least one binding before being able to get Bindings of the Windlord.

3. When you initiate dialogue with [npc=91570] (40.87, 81.01) you must be in Outlaw spec to be able to see the options necessary to unlock the quest. I tested this by switching to both Assassination and Subtlety right in front of her and then speaking with her in each spec; the options were only available as Outlaw.

4. According to other sources you must choose the 2nd dialogue option "I have no desire to imprison the Windlord. I wish to come to an arrangement with him." in order to properly proceed through the dialogue chain and be able to accept the quest. I have not personally confirmed that choosing the 1st dialogue option bars you from accepting the quest.

5. You do NOT need to be in Outlaw to loot the bindings. I received mine as Assassination.

6. ****IF YOU GO TO THE TOP OF THORIM'S PEAK AND CAN'T SEE THRYMJARIS**** It means you have not completed Heart of a Dragon and/or Where Dragons Rule, which are part of the Trial of Will chapter of the Stormheim campaign and are necessary to get Thrymjaris to appear on top of the mountain (at 40.87, 81.01).

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• If you DID complete the aforementioned quests as one faction, but then transferred your character to the opposing faction and can no longer see Thrymjaris atop Thorim's Peak, it most likely means that your entire Stormheim campaign was reset when you transferred factions (this happened to me).
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• To properly begin the Stormheim campaign after transferring factions, go to the Violet Citadel in Dalaran and receive the quest A Royal Summons from [npc=96644] (A) or the quest The Warchief Beckons from [npc=96683] (H).
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• Proceed through the first three chapters of the Stormheim campaign until you begin the A Trial of Will quest line, which will lead you to Heart of a Dragon and Where Dragons Rule, at which point you will properly be able to access Thrymjaris once again and can proceed through her dialogue options to get the quest.
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I will update this comment if I come across any other special circumstances, but if you keep the above list in mind it should be smooth sailing!

If you select the wrong dialog option, just join an arena skirmish and leave, then you can re-select the second option.

Ixzo has obtained Thunderfury! Proof can be found here: http://www.mmo-champion.com/threads/2070940-Thunderfury-Hunt-READ-THE-OP-WE-FOUND-IT!.

Here is how you obtain Thunderfury, Hallowed Blade of the Windlord:

You need Aritfact Knowledge Level 5 to obtain a [item=139466] from Dargul in Neltharion's Lair on any difficulty (excluding Mythic+).
You need Artifact Knowledge Level 6 to obtain a [item=139468] from AshGolem in Vault of the Wardens on any difficulty (excluding Mythic+).

There are no reputation requirements for this at all (see here: http://us.battle.net/wow/en/character/frostmourne/Klaes/reputation/ . As of this post he is only exalted with Nightfallen but that is not tied to the bindings at all).

After you obtain your first binding (regardless of which boss you get it from) you need to speak to Thyrmjaris ([npc=91570]) in Stormheim. You need to be in Outlaw spec when you arrive in order for her to give you the quest Bindings of the Windlord.

After you've obtained the quest then need to kill whichever boss has the remaining binding (ie if you received a binding from Dargul you would then, after accepting the quest, need to kill AshGolem). Return to Thrymjaris with the 2nd binding and 10 Infernal Brimstone. She will then summon Thunderaan and you'll receive Emanation of the Winds which grants you the Thunderfury, Hallowed Blade of the Windlord appearance!