Here is the full list of all 23 Zwei: The Ilvard Insurrection achievements.
Defeat Arch Shelob and recover Alwen's Quake magic.
Defeat Ephemeroga and recover Alwen's Freezing magic.
Defeat the Abyssal Flower and recover Alwen's Whirlwind magic.
Defeat Fafnir and recover Alwen's Inferno magic.
Reclaim Castle Moonbria.
Defeat Galgarion and claim the key to Luna Mundus.
Defeat Zahar in his true form in Luna Mudus.
Defeat Thermidor in the Spiral Fortress.
Defeat Lucian the Gilded.
Collect all armors for Ragna.
Collect all armors for Alwen.
Collect all accessories.
Collect all widgets.
Obtain every type of food at least once.
Complete the trading sequence and obtain Ragna's Spiral Gear.
Learn all of the Arcanum combo skills.
Earn a cumulative total of 500,000 penne.
Raise all pets to level 9.
Discover all three pieces of info about every character.
Defeat the mightiest challenger in the G-Colisseum.
Conquer the Illusory Labyrinth.
Earn the "Ace Hunter" Treasure Hunter rank.
Take hot spring baths with Subaru, Odessa, and Alwen.