"It does nothing!" Her shaking is enough for him to catch his balance again, even if he still doesn't look like he has the will to continue fighting. He stares at the fighting, where some indistinct people-shapes are trying to help and then cry out with warped-but-familiar voices at the soldiers turn their attention. The fire from the next spell bowled some of the soldiers, but weakens with every pained cry, as if Duke is getting hurt rather than the other 'people'.

"Nothing I do aids, it never did!" That may be the biggest hint that this isn't a completely unfounded nightmare.