Herald of the Goddess

I wasn't able to find any exact instructions on how to get this mount, and nothing within the game really guides you towards it, so I was a little confused after collecting all the shards. Here's a step-by-step guide to the entire process:

Make sure you have an empty bag slot and some method of slow fall (see step 6 for some suggestions).

1. 
   
2. Go to Kuri and pick up Tales of the Sky and Ugh, Chores!. Complete the entire quest chain up to and including The Legend of Aln'sharan. This will enable you to collect [item=255826] and award you 5 to start your farm.
   
3. Collect 500 [item=255826]. After having completed the questline from Kuri, these will occasionally drop from mobs around Harandar. The droprate is quite low as you can imagine, so expect either to slowly gather them over a long time, or to invest a few hours into farming them.
   
4. Once you have 500 shards, go back to Kuri at /way 66.2 25.4. You will get an extra action button to toss your 500 Shards into the water, as she did - do it.
   
5. Find Aln'sharan who will be flying in the north-west part of Harandar. He moves around so I can't provide exact coordinates, but he's hard to miss. Notice that your cursor should turn into the gear icon when you mouse over him, meaning he can be interacted with.
   
6. You will take damage when near him, so do step 5 quickly before you die. While in close range to Aln'sharan, dismount in the air and interact with him (right-click). From my experience, you cannot interact with him while mounted. Using steady flying instead of skyriding may help you position.
   
7. If you have any means of slowfall (priest, mage, demon hunter, glider, druid, parachute, Skyguard's drape, Fangs of the Father, etc) or ways to clip your fall (warrior, hunter, goblin, etc) use it now or you will probably fall to your death!
   
8. The mount [item=256424] will be in your bags. Once you learn it, you will receive this achievement.

Once you have completed the [storyline=5909] storyline, mobs in Harandar will start dropping [item=255826] rarely.
The version of [npc=242358] that wants the 500 [item=255826] is located at /way #2413 66.15 25.47 Kuri for skyshard hand-in.

This leads to completion of this achievement and the [item=256424] mount.

Rare flies high, around Har'kuai, Village of Rain

TomTom coordinates: /way 60 20