The Luck enchantment can deal additional damage with each hit. The effect is based on the weapon's level and provides a chance for extra damage beyond the normal attack damage.
Mechanics
Each hit has a chance to deal additional damage based on the weapon's level
For each level of the weapon, it makes an additional damage roll that could exceed the original damage
The higher the weapon level, the more potential for additional damage
The effect is variable and not guaranteed to increase damage every hit
Technical Details
Additional damage = max(0, attacker.damageRoll() - i) for i from 1 to (weapon level + 1)
This means it tries multiple times to exceed the original damage, taking the highest extra damage value
The calculation is: for each level+1 attempts, it takes the maximum damage that exceeds the original damage by i points