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