Hey! You requested this review from me awhile ago, but I fail at keeping up with my queue. Sorry, but I am here now. :)
You mentioned one of your concerns being grammatical mistakes, so I'm going to open with that.
There's a typo in the chapter summary - I'm assuming wepon should be weapon. You also don't really need the ellipsis - an ellipsis should indicate that you're leaving something out, but that seemed like a full sentence to me.
First paragraph, second sentence: not being able to fight would sound better as unable to fight. It can get confusing when you're combining several different descriptions into a single sentence, but an easy way to judge whether something's grammatically correct or not is to pair each part with the beginning of the sentence to see how it sounds. For example, this would read, There was no princess, not being able to fight. That doesn't really work. There was no princess, unable to fight, on the other hand, does.
First paragraph, fourth sentence: like parents would do that anyway seemed a little out of place to me. For one thing, there are parents who would do that, especially in fairy tales, and for another, it's not like Harry or Ginny haven't seen enough of human nature to know that. It also felt like a rather abrupt deviation from the overall tone of the piece - it's kind of mystical in the beginning, and that just felt like an awkward aside. It would work in some narratives, but I don't love the way it works here.
Second paragraph, first sentence: the use of but in this sentence felt awkward to me. But is generally used to contradict or contrast something with something else; there's no conflict between a girl being like a dragon/turning into a flame and burning down his world. If you wanted to emphasise the bit about her being a tiny flame but still powerful enough to burn down his world, I think it could use a bit of rephrasing.
Third paragraph, third sentence: I'm not quite sure what just the kind you wouldn't expect to be one means. (I'm assuming that except should be expect.) Was he the kind of person you wouldn't expect to be a warrior, or just a particular type of warrior? It's a little awkward, and I'd suggest you rephrase it.
Fourth paragraph, first sentence: There should be a comma before though. I'd probably change the comma after it to a colon or a dash, but that's less of a big deal.
There are a lot of other instances of misused commas, but I'm running out of space, so I'm going to stop there. Be careful with your comma usage; you sometimes omit them where they're necessary or use them where a different method of punctuation would fit better. I saw that you've already had this beta-ed, but I'd suggest asking around to see if there's anyone who's particularly good with commas who can point out the problems.
In more general terms:
Be careful with your tenses. You switch around between past and present several times in the opening paragraph, stay with past for a bit, and then switch back to present at the end. I'm not sure if it was an intentional stylistic choice or not, but whatever the reason, it didn't work for me.
I'd also recommend trying to use a little more variety in your descriptions. In the fifth paragraph, you use around her legs, around her arms, and around her hair in quick succession. At the end of the paragraph, you do the same thing with the word fast. Sometimes repetition is good, but it needs to be used in moderation or the description just ends up feeling flat. For example, rather than reusing around three times, you could have said, Fire was blazing around her legs, twining around her arms, licking at the edges of her hair. Okay, that's not the greatest example - I'm a bit tired - but do you see what I mean?
Your characterisation was good - I'm not sure that canon Ginny and Harry were quite what I thought of when I read this, but I think you have some room to play with it, and I like the idea of them joking around about sword fighting as an escape from life in general. I certainly didn't feel like this was opposed to the canon portrayals of them, and for Ginny in particular, once I stopped to think about it, I thought this complimented what we saw of her in canon nicely. (I did, however, think that Harry walking her home to the Burrow didn't quite fit with canon - wouldn't she just apparate there? I doubt he lives in the middle of nowhere.)
Along those lines, I do really like the concept. You mentioned being worried about the idea because you sometimes think that you have a great idea, but it ends up not working out well. I think that this is an absolutely lovely idea. It's imaginative and it's fun, and I really enjoyed reading it. It's a sweet little look at them, which is something I think that you do quite well in general.
So, great concept. The execution, however, could use a little work. It's not that I don't like it - as I said, I do. I just feel like your descriptions were sometimes overly vague and confusing during the fairytale-type part of the story and just not detailed enough at all at the end, which felt like it was mostly dialogue.
There was one thing that stuck out the most to me as I was reading: you talked a lot about fire throughout the fic, but you never really went into any detail about it - you just basically seemed to use "flame" and "fire" a lot. Since fire is such an expressive thing and kind of lends itself to creative use in a description, I'd have liked to see a little more of that. The language you used was sometimes flowery, but I didn't feel like there was enough in the way of compelling description backing it up and really making the piece stick out.
And I've run out of space. I hope you found this helpful, and I'm sorry again about the delay!
Author's Response: Wow.
Um...thank you. Seriously, how do you have time to write your own stories? You put so much effort and time (not that I am complaining or that you shouldn't) but wow, you really work hard, and even if you didn't like the story that much, you at least put a lot of effort into this review, and for that I thank you.
Well onto replying.
grammatical mistakes shall always be my problem, and without my beta I would be lost, and I thank you again for spending your time going through all of them, and I agree with you, they're a lot of things that could sound better, it's just sometimes I need someone other than me to point it out...Does that make any sense?
This was actually really good: Don't put yourself down, this example was amazing: (Fire was blazing around her legs, twining around her arms, licking at the edges of her hair) For somebody that is tired you write like a pro.
Thank you for all the help, I think I will work on it a bit more, and maybe go back and fix some of the things, because this one-shot is the kind I really just got into, and I want to do well.
Thank, thank, thanks so very much, and I am really, really happy that you liked the idea of it, and I am so happy that you spent all this time helping me on this, thank you very much!