You can obtain this Hunt after you have saved Ashe from the Dreadnought Leviathan and after she joins your party for the remainder of the game. The fight is fairly easy if you still have Vossler on your team as he can use the 
Telekinesis Technick to aid you during the fight.
Sherral - an Imperial Soldier who can be found on the upper floor of Amal’s Weaponry shop in Rabanastre.
The Wyvern Lord can be found flying around in the northwestern section of the Nam-Yensa Sandsea. You can get there easily from the Tomb of King Raithwall by exiting the tomb to the east into the Trail of Fading Warmth in the Nam-Yensa Sandsea and then traveling northeast into Simoon Bluff. The Wyvern Lord is in the northern area of this zone.
Level: 18
HP: 18,669
Steal: 
Yensa Scale, Crooked Fang, Wyvern Wing
The most difficult part of the fight against the Wyvern Lord is dealing with the fact that it is a flying-type enemy that cannot be hit with regular attacks. Setup your party with any ranged weapons or Magicks as their primary method of attack. Guns, Bows and Magicks are your attacks of choice; Vossler will be just fine attacking if you have him in your party as he can use the Telekinesis Technick to attack flying enemies.
Make use of Quickening attacks if your party has access to them but make sure to do this effectively so that you don’t wind up with a full party of characters who have no MP (and therefore cannot heal). Check out the Quickening tips section for more information. Make sure that you avoid using Wind-based Magick such as 
Aero as this will heal the Wyvern Lord instead of damaging it. 
Dark Magick is extremely effective if you have access to it and remember that you can swap in other team members if they have Quickenings to start a Quickening chain again.
A video of the battle in the Zodiac Age version is included below:
Return to Sherral in Rabanastre once you have killed the Mark. The reward for hunting down the Wyvern Lord is 1,000 gil, a 
Longbow and a 
Shell Shield.
