The older kits usually were over optimistic about the finished weight. It will probably fly ok with the Medallion. Are you using light weight foam wheels? Maybe loose a few grams there. Also, I have been using the 7-9 gram servos in 1/2A planes for years for a nice weight saving. Your battery seems fine. Did you weigh it on a fisherman's scale? They are usually inaccurate to the heavy side
