Here is the full list of all 49 Nights of Azure achievements.
Viewed an extra ending.
Actualized 40 Servans.
Arnice achieved her max level.
Defeated Christophorus.
Defeated Mistral.
Achieved 500-Chain.
Transformed into Nightmare form.
Transformed into Phantom form.
Viewed an ending.
Defeated Ludegert.
Maxed out a Servan's level.
Defeated Corrine.
Arnice equipped Hamelin's Pipe and cleared a battle.
Arnice equipped Glass Blade and cleared a battle.
Gave 1000 orders to Servans.
Defeated Blueblood Dragon Mavelus.
Collected 50% of items.
Defeated Blueblood Maiden Milaya.
Defeated Blueblood Count Rosier.
Collected 50% of Servans.
Transformed into Armor form.
Summoned a Servan 100 times.
Executed a trade for the first time.
Transformed into Rabbit form.
Defeated 1,000 enemies.
Defeated Blueblood Cavalry Carousel.
Achieved 300-Chain.
Gave 100 orders to Servans.
Cleared first Arena task.
Completed first task.
Defeated Blueblood Dragon.
Achieved 100-Chain.
Transformed into Demon form.
Actualized a Servan for the first time.
Defeated 100 enemies.
Gave an order to a Servan for the first time.
Summoned a Servan for the first time.
Collected all achievements.
Summoned Servans 1000 times.
Actualized 80 Servans.
Executed trades in half of the world.
Executed trades all over the world.
Completed 100 tasks.
Completed 300 tasks.
Cleared half of Arena tasks.
Cleared all Arena tasks.
Collected all Servans.
Collected all items.
Defeated 10,000 enemies.