I often see this guy at the loc someone else gave, neg 2007 neg 728 near Cabilis. And indeed, when I finally decided to work on getting Greenmist for my SK, I found him there. I went off and killed giants to get the misscribed spells he wanted, and came back and he was still there. I paused to cast Identify on the spells just so I could report the results, and when I looked up again he was gone!
So I ran back to the giant fort and fortunately found "a forest giant" in the room where he sometimes spawns. As usual, he said something about not letting a lizard escape. I've killed him many times before and never seen anything pop out, so I assumed the quest had been changed so the knight was always at Cabilis and the giant's text just hadn't gotten changed. But this time, when I killed the giant, "an iksar knight" really did appear and started running out of the fort toward Cab. I hailed him en route and he stopped, so I gave him the items he asked for and he despawned. I guess I should've waited and done it closer to Cab so I could follow where he went afterward. Oops!