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