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