Reset Yuan Shao and max out lubu with your third weapon.
Then go to the batle of hu lao gate and do: at the hard dificult seting, put yuan shao to safety and kill diao chan with cao cao, liu bei, sun jian, lu bu alive, before ambush event, do all with lu bu as 2nd player and yuan shao as 1st. figth only with lu bu.
Finish the level andreset lu bu and max out yuan shao, if the impireal saber unlocked(weapon).
Then go to the batle of chi bi. on lu bu forces on the hard dificult setting.
With lu bu and yuan shao. lu bu- 1st yuan shao- 2nd with yuan shao kill every oficer in the north, and make sure you kill dong zhuos sub oficers on the left side of the map and oficers to insure lu bu safety, ten minutes in the game and enemy rienforcements will apear.
Defeat in order: lu meng; huan gai; taichi ci; gan ning, a valuable item will apper on the down/left side of the screen, defeat guo si and li ru and go cath the item and defeat dong zhuo