That's my question, does it increase the spell dehate by an additional 8% (which would be amazing) to a total of 14% or it overrides the previous effect and and technically only increases by 2% (6% on the original to 8% on the modified). Personally I think the latter because SoE (at the time) wouldn't have given such a huge jump in the effectiveness of the 2.0's worn buff.
But that's just me.