If you look at my mortems, you'll see that I play glass cannons almost exclusively. I rely on avoidance/sheer killing power so much, that if I take any defensive traits at all, I take them very late. For example, my standard build is SoB->SoB->TH->TH->Rel->Rel->MAc->Fin->Fin->WK->WK->Fin->HR->HR->HR->DM->SoB->SoB->SoB
Overall, I've found that on harder difficulties, the main thing is that you can't let yourself get shot at. You have to kill enemies first, and then that requires that all your effort goes to killing as efficiently as possible.