Woah, I...do not know what to say. This chapter was just...wow. Amazing job, I'm now as hyped as ever for more. 
Few things though: in CTDS, Mystics are called Fiends. (Magus is also called the Fiendlord, a much more accurate translation, as his original title meant "Dark King" or "Witch King") A much better translation, seeing as the Retranslation reveals their names to originally be "Demons". Also, the Shiva Edge (or Onimaru, I think it's called in CTDS) is actually Crono's second best sword, not the Swallow...but I think the Swallow's cooler, so it doesn't really matter much. :p
Nice job with adding that little tidbit about strong willpower needed to maintain the Rainbow. Makes sense. Also, why would Crono say that "we have no future" when he himself saved the world from Lavos? I guess because the ruined future is such a horrible and vivid memory to him. Even so, though... Bah, I'm sure you'll have a good reason. :p Eagerly waiting to see who the mysterious challenger is, also.
All good points, Chocobo Fan, you're extremely astute, and you keep me on my toes (a good thing!), though in this case I do have my reasons. I'll give them to you now:
1) Mystics vs Fiends
I thought for a long time about this before writing this chapter. In the end, I decided I simply like the name Mystic better. Fiend to me is too strong a word of fear, while Mystic brings up thoughts of the unknown. I like the idea that people fear what they don't understand, and ignorance is one of the themes of this piece, so Mystics works better for me, cool as "fiend lord" is. The new translation definitely favours Fiends, of course. It also makes sense, as it seems a fitting word for the people of Guardia to apply to the little conquering mutants. So I've opted for style over sense, here.
2) Shiva's Edge
Another one I thought long and hard about. In the end, I decided, as you did, that the Swallow was cooler. I also like the connection to Chrono Cross, and because this story links the two timelines (though not directly), I went with that. I also like that the Swallow is a shorter blade in the illustrations, and I wanted Crono to have both a long and short sword. I suppose Shiva's Edge is actually short, as well, though. But Shiva's edge? Too much connection to Hindu mythology that I didn't want to have to explain. Glad you like the willpower bit. Thought that up on a whim, and liked where it was going, so I stuck it in. Keep an eye on that...
3) Crono and future
This is a good question, and I'm glad you brought it up. First of all, Crono is, of course, quoting Azala, who's dying moment was one of my favourites in the game and still hits me in the heart (and since I was "playing" Crono in the game, I assume it hit him as well ^_^). What's happening here is that he's sympathizing with the sentiment. What's funny about Crono is that he's saved the future of his planet only to find himself living a life he doesn't want. So in his mind, he's sacrificed his own future to serve his people.
As for who the stranger is, of course you'll just have to wait ^_^
