Well, I finally got around to re-doing this image from scratch. I believe that thanks to all above, it is a huge improvement. There is a great lesson for those who continue to follow the thread. As we saw that the thin light blue (actually CYAN) line was present to some degree in the original, I went to the Lens Correction tab in ACR, set FiIx Red/Cyan Fringe to +30 and selected Highlight Edges from the drop down menu in the Defringe box. (Not sure if the latter did anything noticeable but I figured it could not hurt.) IAC, the CYAN line pretty much disappeared.
To prevent loss of detail in the breast feathers I used Curves rather than Shadow-Highlight to lighten the middle and darker tones and it seems to my eye that the fine detail has been preserved.
Thanks again for helping me improve this image with better Image Optimization techniques.