This is an optional boss in a secret area, see this solution for getting there:
There is a gimmick for one-shot killing this boss (I'm not sure that it's possible to engage it normally, anyway).
*** Spoiler - click to reveal ***As soon as the battle starts, run straight and then head to the left. Unlike other boss battles, this area is large and somewhat open- you aren't confined to a small area. You'll follow a mostly linear path with several enemies. You'll eventually work your way around and to a building entrance and you'll see a ladder that leads onto some scaffolding. Climb this ladder, head left, and drop to the platform below, then to the next (stone) platform. From, here, you can do a plunging attack (press 
while falling) to execute an attack that will instantly kill the wyvern.