How many Yilbegans have you battled in total? I have popped him in the glacier before but definitely give it another shot, although I think its total luck of the draw.

Have you ever seen rings or titles drop from non shadowed version?

As for HQ/NQ maybe it just seems HQ due the how much time spent in specific forms that have higher damage reduction. I know for a low man group the difficulty in defeating him has varied a lot, so much it seems like there is a higher tier version. Least that has been our experience anyways.