Same problem and I found no solution it's another Dragon Age bug that you're forced to live with I suppose. What I basically had going on for the Grand Duchess fight was a fully red health bar on all my party members no health potions I'm stuck in a Nut Cracker uniform with like 10 Defense and on all top of all this the game bugs and resets everyone's weapons into these tier 1 defaults so like Sera is maxed out with an archer skill tree but now she has tier 1 iron daggers and can't use any abilities for any reason. I love Dragon Age but at the same time, someone was in charge at double checking something to make sure you wouldn't deal with this much ignorant frustration during a boss fight, let's fire that guy and beat up his family.
