Here is the full list of all 14 Soulslayer achievements.
Complete main story and reach good ending
Eye for an eye
Complete Yaohongyuan's route
Save all three from the fire
Complete Zhencheng's route
Complete Junyue's route
Make a successful deduction
Reach a dead end
Complete Lady Xu's route
Refuse to do anything until run out of chances
Poison yourself for all three times
Complete all the routes
Drink the poisonous soup twice
Complete tutorial level