Here is the full list of all 24 Skyborn achievements.
Defeat Qua'Lon.
Defeat Dhacian! Big surprise huh?
Find St. Theresa's Battle Armor in the big chest in the Celestial Nexus.
Defeat Shynn.
Defeat the Titan.
Return Laryn's wedding band.
Unlocked the second class change.
Defeat Fafnir.
Defeat the Sand Dozer.
Unlocked the first class change.
Defeat the Lamia.
Find the Stylish Hat in the big chest in the Coal Mines.
Find the Circuit Breaker in the big chest in the Coal Mines.
Find the Sapphire Bracers in the big chest in Granminster Prison.
Successfully defeat the sky patrol.
Celebrate achievements being added to the game! Thanks for waiting!
Unlock the final class change.
Complete the Experimental Potion for Atlas.
Finish Alda's Trial of Arms in record time!
Defeat Saehral.
Defeat Dhacian on Hard difficulty.
Defeat Qua'Lon on Hard difficulty.
Complete the arena.
Collect all Spades cards, and clear the Venom Depths.