Conquer Miko Ins after get 2nd spd book at turn 16.If his mood is at 7, it will give him an auto power up. The start of turn 13,Rance will get an event which gives him 1 affection. At the end of turn 12, Rance's mood must be 7.Conquer Mamushi oil field before turn 12 and impose levy to get 1 atk book and use it to Rance (atk 5->6).At turn 6 and 16, try to get 2 spd textbooks (spd 4->6).Here is what I do to up Rance to a godly unit at early-mid game: I'm doing a 5-star no bonus at the moment and upgrading Rance's stats is actually the best thing I can do if I want to win the game by conquering (and completing all achievement as well). If you do, you gonna have better units at the begin of the game, so upgrading Rance is not the best thing you should do (but you definitely need it if you want to get "fuck 300 women" achievement). A points runner poster a guide a while back.Attack luck will work for both troop and commander battles however. You will not be able to use charge, commander charge, etc and most passives like Hibachi or Lover will not work.
In commander battles, only basic skills will be available.