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