Yeah I found all of that… So I'm thinking I did something out of order, which created a bug in the quest. Having the "noonwraith" info from this site, I simply waited until noon, it showed up, I took a few whacks and then it disappeared (before I could kill it). Meanwhile it updated my quest and creature manual so that I can now proceed.
That said, I never would have waited until noon on my own, so I'm not sure why my game didn't update before. It has me wondering how many other quests I'll break since this was my first one!
Either way, moving on… thanks for assist.
Maybe if you went at noon again it would reappear - it's quite useful to kill it as it may have some quite useful loot (hint: its green).
I also broke a quest on my first run through the starter area, by not reading the note before doing the treasure cache quest. And also I didn't follow the NPC that gets on a horse quickly enough- so failed that:
Hence, after restarting, I'm being much more caerful and keeping named saves as I go along and tick off some important progress - you can change the name of your saved games by going into the save directory in windows explorer (sort by modified date and rename the last manual save and it's associated png to the same name).