m_s0 said:

I get that, but I'm not sure the phrase "the ancient fear" makes sense on its own if you dissect it. That might change when we learn of the actual context.

I was just reading through a SW Thread on another site, and they say its is referring to Max Von Sydow's character, who we can all assume is playing the villain now.

I wonder if he will be an older (ancient) Sith, who was trained by The Emperor just in case Vader didn't live up to his jedi abilities after falling in the lava pit?

Just a guess and pure speculation on my end.....