Wouldn't it make sense to have a "Warring Kingdoms" leader board? Calculation could be quite simple.
War win = 1000 base points * kingdom relative size %
So if you beat a kingdom 80% of your size, its 800 pts. If you beat a kingdom 120% of your size its 1200 pts.
Could even throw in some menial points for draws:
Draw = 100 base points * kingdom relative size %
So if you draw with a kd 80% of your size its 80 pts. If you beat a kingdom 120% of your size its 120 pts.
For a game that is supposedly focused around kingdom warring, I'm actually quite surprised this does not already exist. Are there concerns with such a leader board that I am overlooking?