Here is the full list of all 39 Cathedral achievements.
Find all armor augmentations
Destroy an electric orb in Necromancer's den using the lantern
Have more than 25 000 gold stored in the bank
Have more than 50 000 gold stored in the bank
Buy the Tourmaline armor
Buy the Onyx armor
Find all map pieces
Acquire all health bottles
Return 100 books
Find all ammo upgrades for the Magnus Apparatus
Buy the Emerald armor
Complete the game without upgrading the armor
Kill Ardur
Find all ammo upgrades for the Flintlock
Destroy the Conduit
Kill Nidlong
Acquire all Ouroboros amulets
Return 80 books
Find and activate all portals
Kill the blood knot
Have more than 10 000 gold stored in the bank
Find all charms
Find all hearts
Kill Oloc
Slay all gargoyles
Kill Thalia
Return 60 books
Return 40 books
Die one hundred times
Kill Salemacke
Kill the Necromancer
Return 20 books
Kill 150 blobs (of any kind)
Kill 150 skulls (of any kind)
Kill 100 skulls (of any kind)
Kill 100 blobs (of any kind)
Kill Augr
Kill 50 skulls (of any kind)
Kill 50 blobs (of any kind)