Here is the full list of all 15 Abberbury achievements.
Kill your first enemy
Die on spikes
Destroy a ballista
Die under a platform
Die under rope-rock trap
Break all barrels
Kill a lion
Kill all enemies at level 15
Kill Hrottgar, the Javelin Thrower
Kill El Gimor, the Alchemist
Kill sir William, the Guards Chief
Kill Ildred, the Executioner
Kill Norton
Complete the game without dying
Find the secret room