XXX of Lightning is a suffix that can appear on Magic and Rare Items. It provides a chance to proc Lightning.
It doesn't start spawning on items until Item Level 18.
"On attack" means every time you swing your weapon, "On striking" means when you land a blow, "When struck" means when the enemy hits you.
Stats[]
of Lightning
5% Chance to Cast Level 3 Lightning On Attack
Can appear on: Magic Items, Rare Items
Is available on: Melee Weapons, Throwing Weapons (except Amazon Weapons)
Items
Chance to Cast on Offense — of Fire Bolts • of Ice Bolt • of Nova • of Lightning • of Chain Lightning • of Amplify Damage
Chance to Cast on Defense — of Charged Bolt • of Frost Shield • of Nova Shield • of Hydra Shield