Executioner
Executioner increases critical hit chance. It is a distinct critical-hit choice, while Kingslayer increases critical hit damage and Mind's Eye increases ranged damage.
How it works
The Traits source says Executioner increases Critical Hit Chance by 1.25% per Trait Point invested, up to a listed 25% bonus at Level 20. Kingslayer has a separate listed effect for critical hit damage. The supplied evidence does not describe how these effects interact in a particular build.
When it helps
Consider Executioner if critical hit chance is your intended focus. If you want to increase critical hit damage instead, compare Kingslayer; do not treat the two descriptions as interchangeable.
The tradeoff
Executioner changes critical hit chance; the source lists critical hit damage as a separate Trait effect.
Your next step
Choose whether your stated priority is critical hit chance or critical hit damage, then review Executioner and Kingslayer.
Read the supporting references
Check the edition and source version for patch-specific details. Guide methodology.