Why do staff in weapon slot 2 not alter stats

I equiped a staff with +3 lightning skill plus lightning damage. but my stats don't change when I equip it. I'm a sorceress. do weapon slot 2 stats not count?

As weapons in the 2nd slot are not technically equipped, you won't receive any of the modifiers or unique powers unless you weapon swap. Though when you weapon swap, then you'll lose your modifiers/unique powers on your 1st slot until you swap back.