Since I recently wrote about my grading, I thought I would add links to the U.S. Naginata Federation's standards for ranks. I make no claim as to how accurate or current these are. As far as I recall, at least for kyu rankings they match up with those of the All Japan Naginata Federation, but don't quote me on that!
USNF Standards for Kyu Examinations
USNF Standards for Dan Examinations