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