Celtic Heroes

Hi, i recently traded my legendary black nightwing, the second rarest nightwing and was wondering if i did a good deal. i want to know how much it aproximately costs in morrigan. in my opininon i was thinking its around 5m. i traded it for a spectral ring of the reaper which i was trying to get without luck. i got my nightwing from chest btw.
so, am i missing somthing? like is it maybe worth more, or did i just do a good deal? cuz as far as i know reaper ring is worth 7,5m+.