First you have to complete the game once (you don't have to get all the attacks, just beat Sauron at the end of Pelennor fields.) Then start a new game. Save it and exit.
At the main menu, go to more, then evil mode. Load it as your completed game. Select a level, e.g Minas Tirith, and do the level. When you get your stuff save it to your new game. Then load up your new game and go to 'Equip'.
If you do Minas Tirith, Berethor should have the best lower body armour he can get ( darkened Numenorian steel fauld, armour:68, 5star.) Also he should have Sword of Isildur, High king of Gondor, damage: 205, 5star.