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