Lightning Skill

The lightning skill says it has a 3-11 sec armor debuff.

Does anyone know:
1) how much it debuffs by?
2) if it stacks?
3) if it increases by rank?

That is all

Thanks

Tried it out before when i was 50 in cosmo, i hit my friend, a mage in void in pvp. According to him my lightning only does -2 armor debuff. I have 5 pts and i have 128 dex and 126 int at the time of test