Shadow of Mordor crazy difficulty spike after beating the game?

I finally managed to beat the game and now working on cleaning the map and some trophies. However the difficulty seems to have spiked up that makes things almost impossible. I have uplocked all the skills and all my weapons have yellow/orange epic runes, but somehow I get one shot by the war cheifs.

Do I need to keep dying for the game's world balance out or the game just becomes super difficult after beating the game? I think I died a total of maybe 3-4 times during my whole playthrough but now I keep dying everytime I encounter a war cheif or even a low level commander.