How is it MUCH? If you take an epic chaos chaosblade with an extra 2d8 dmg, thats an average of 9 dmg, 5d6 becomes 17.5. So, 9 extra dmg to each hand or 17.5 dmg to the main one weapon doesn't sound like "MUCH" of a difference. Thats almost essentially how power attack is working right now off a characters strength modifier. Two characters running a 50 strength, the TWF is getting +20 to each hand and the THF is getting what...+30?
People who say that deadly weapons were overpowered on ESOS should quit whining...it simply isn't true, and there's a ton of practice to substantiate that.
I mean, what the hell are you going to comapre the sos to? A light pick? Compare it against weapons that people would want to use at end game...such as the chaosblade example I provided.