Board Thread:Dark Souls II/@comment-24129583-20140512025233/@comment-24721972-20140515133357

The lightening infusion decreases your strength scaling but increases your faith scaling with lightening damage. So you'll do less physical damage but more lightening damage. If you don't have a lot of faith you'll end up doing the same or less damage because the amount of damage is increased by faith on a lightening path.