Here is the full list of all 49 Nights of Azure achievements.
Collected 50% of items.
Defeated Blueblood Maiden Milaya.
Transformed into Phantom form.
Summoned a Servan 100 times.
Collected 50% of Servans.
Defeated Blueblood Count Rosier.
Executed a trade for the first time.
Defeated 1,000 enemies.
Gave 100 orders to Servans.
Defeated Blueblood Cavalry Carousel.
Achieved 300-Chain.
Cleared first Arena task.
Completed first task.
Defeated Blueblood Dragon.
Transformed into Demon form.
Achieved 100-Chain.
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 Mavelus.
Defeated Corrine.
Defeated Ludegert.
Defeated Mistral.
Defeated Christophorus.
Viewed an ending.
Viewed an extra ending.
Summoned Servans 1000 times.
Gave 1000 orders to Servans.
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.
Achieved 500-Chain.
Defeated 10,000 enemies.
Transformed into Rabbit 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.