Here is the full list of all 43 Banishers: Ghosts of New Eden achievements.
Successfully give Antea her ascent
Defeat the Nightmare
Defeat Calendre
Activate all Shelters in New Eden
Equip 8 items at rank 7 (Relic) at the same moment
Solve all the Haunting Cases of New Eden
Freeze 5 enemies in a single encounter
Defeat 50 enemies with a Banishment
Collect 10 000 Pieces of Eight
Choose the destiny of Captain Pennington
Defeat the Puppeteer
Reaffirm your Oath
Defeat Aul' Saul
Choose the destiny of Fairefax Haskell
Defeat the Infamy
Destroy 300 destructibles
Upgrade an item at rank 7 (Relic)
Defeat the Specter of a banished ghost in the Void
Defeat 5 enemies with a weakspot hit (Rifle) in a single encounter
Defeat 3 enemies with a single Outburst
Choose the destiny of Thickskin
Defeat the Beast
Defeat at least 4 enemies with Red and at least 4 enemies with Antea in a single encounter
Defeat 8 enemies in a single encounter without being hit
Take your Oath
Upgrade an item
Find Antea
Unlock all achievements
Successfully bring Antea back to life
Find 15 Bibles for Hugh Batcheler
Find the old writings by the Brotherhood of Saint Paul's Stole
Unlock the secret passage in Bligh Manor
Defeat 3 enemies with a post parry attack in a single encounter
Complete the same Ritual site 10 times (intensity level 10)
Defeat 50 enemies while Fusion is active
Unlock all locked chests in New Eden
Unlock all cursed chests in New Eden
Complete all Haunted Grounds of New Eden
Collect all Collectibles in New Eden
Find 50 Soul Grabbers in New Eden
Complete all treasure maps
Collect all 88 available equipments
Reach level 25