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