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