Here is the full list of all 33 Witch Thief achievements.
Fire 100 bullets!
Fire over ONE THOUSAND BULLETS!
WHAT'S YOUR BULLET COUNT?
Fire over ten thousand bullets!
Fire over one hundred thousand bullets
Fire over one MILLION bullets
The first of many
The bullets still hurt you
Death by a Thousand bullets
You have passed through the forest
You are the master of the woods
You have passed through the Castle grounds
You are the master of the Halls
You have passed through the Cathedral
You are the master of the Cathedral
You have passed through the Library
You are the master of the Library
You have passed through the Throne Room
You are the master of the Throne
Complete the Story as the Witch Thief
Complete the Story as the Witch Sage
Complete the Story as the Sword Maiden
Complete the Story as the Doll Maker
You have bested her in combat
You have freed her mind from corruption
You've destroyed 100 props!
You've destroyed 1000 props!
You've destroyed 10,000 props!
You destroyed a Jack-o'Lantern
You've collected over 100 power-ups!
You've collected over 1000 power-ups!
You've collected over 10,000 power-ups!
Gather all the shiny little crystals