+% Lightning Skill Damage applies a percentage increase to any lightning skill damage (after any synergy bonus), or integer or percentage lightning damage added to any melee attacks of the user (so it applies to the percentage added by Vengeance, but it does not apply to physical attack damage converted to lightning by Lightning Bolt).
- When present on two weapons, the percentages of both are summed and applied to skill damage, and attack damage of either weapon when using a melee attack.
- It applies to skill damage applied by missiles when created, and other damage when applied. If there is a delay between skill usage and missile creation (as there can be with Lightning Strike and Chain Lightning chains, and Lightning Fury and Thunder Storm bolts) or skill usage and damage (as with the first Claws of Thunder charge), swapping weapons or other items to apply a higher percentage may result in more damage. 
- It applies to Holy Shock skill damage before it is added to any attack, then again when using a melee attack.
- Character screen displays it being applied to ranged attack damage, but this is not actually the case. 
- It applies to Shock Web, despite what is displayed by its skill descriptions.
- It does not apply to a missile's own damage, so it does not apply to the nova and bolts released by the last two Claws of Thunder charges, or the piercing lightning bolts released by the second Phoenix Strike charge.
- That equipped by the user does not apply to pets summoned by that user, so it does not apply to Necromages; this includes the sentry traps Charged Bolt Sentry, Lightning Sentry and Death Sentry, and any lightning attack damage of Blade Sentinel, despite what is displayed by the character screen and skill descriptions. 
- It does not apply to Static Field.