Here is the full list of all 49 Nights of Azure achievements.
Gave 100 orders to Servans.
Transformed into Demon form.
Achieved 300-Chain.
Cleared first Arena task.
Completed first task.
Defeated Blueblood Dragon.
Achieved 100-Chain.
Defeated 100 enemies.
Actualized a Servan for the first time.
Gave an order to a Servan for the first time.
Summoned a Servan for the first time.
Collected all achievements.
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 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 100 tasks.
Completed 300 tasks.
Cleared half of Arena tasks.
Cleared all Arena tasks.
Collected 50% of Servans.
Collected all Servans.
Collected 50% of items.
Collected all items.
Achieved 500-Chain.
Defeated 1,000 enemies.
Defeated 10,000 enemies.
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.