What people keep telling you throughout the game is that you shouldn't try to balance darkness and light, instead ncsoft just switched that with "don't give in to revenge hooo~"
Here's some changes that i gathered from other threads:
>In the English version, JSy says the Mark "wasn't meant for you" when you encounter her in Madun's village. This doesn't make sense, since you already had the Mark. Originally, she notices you have it and finds it interesting because she didn't remember giving it to you, so she lets you live because of that. When she encounters you at Hongmoon, she remembers you from the village but notice you don't have the Mark, so she gives it to you instead of just killing you. She orders her minions not to kill you because she wants to see what's up wit dat; you also don't just happen to survive to the surprise of the JSy crew because they know how the Mark works.
>Madun doesn't think you're the chosen one because of visions, he recognizes you from when you saved his village. The other seven think ratboy has been huffing arsenic again.
>Mushin doesn't ask you to choose light or dark, he asks you to walk his path, which is a balance between the two.
>There's a lot more moral ambiguity; several of the "bad guys" aren't just mustache-twirling Disney villains. The factions themselves aren't just good v. evil (which is why you can wear the outfits of "bad" factions), but some of the members are obviously dark chi puppets.
>You don't get warned not to give in to the desire for revenge; the revenge story is one of the most common tropes in wuxia and martial arts stories. You're warned not to try and balance light and dark, because trying to do so drives most people who attempt it insane.