The more alarming thing to me is that should this guy decide to be a tit, he can just insta-kill Thurnan on his next turn - Minor, Move, Standard, Life Suck - Thurnan takes another 9 damage, which will probably put him at or below his Negative Bloodied value = DEAD. And the wight gets another 39 HP back.
Yeah, the wight needs to die - if you guys have any single-target damage abilities, now is the time to use them along with action points.
I still have an action point left, so on my turn I'm going to use Nimble Strike to shift back out of melee with him, shoot him, reload, and then action point to shoot him again. That's pretty much all I've got left at this point. Since Galadren will be still in melee on Dunor's turn, he'll have Flanking vs. the Wight at least - does he have any good rogue powers that could trigger Sneak Attack? Or better, anything that would let him disengage given he's not in a good spot right now. Maybe Shandien could pull the Bleached Skeleton off Dunor by Marking it?