Interesting stuff. I just ran across this issue myself while working on my mod.
Here is my first pass at adjusting the unit power ratings (I also removed all of the tech power ratings and kept only a couple of small building power ratings) - link to unit spreadsheet
My plan is just to adjust the XML values and not mess with any of the underlying computational mechanics. I don't think that adding a percentage bonus due to weapons is necessarily wise either, as many units don't make use of weapons, so you could end up artificially inflating the numbers, which simply results in strange AI diplomacy and behavior.
Here is my first pass at adjusting the unit power ratings (I also removed all of the tech power ratings and kept only a couple of small building power ratings) - link to unit spreadsheet
My plan is just to adjust the XML values and not mess with any of the underlying computational mechanics. I don't think that adding a percentage bonus due to weapons is necessarily wise either, as many units don't make use of weapons, so you could end up artificially inflating the numbers, which simply results in strange AI diplomacy and behavior.