Good question. Clearly the setting isn't one of your unique selling points. If you manage to successfully target the more experienced players, this shouldn't be too much of an issue - give them a couple of pointers and they'll be filling in the blanks soon enough. If you are taking aim at beginner players as well, there should be some indication as to what sets this setting apart from LotR/Warhammer/D&D/etc. I'm not saying it
has to be something entirely different, but especially in the fantasy genre it's easy to be seen as "just another" game (I think, at least, that's how I see a lot of games anyhow). System can definitely contribute to stand apart as a game, and it looks like you've got that covered. Art is another one, and you're on top of that too.
As to setting, I think you have two choices.
1) In a pure fantasy setting, include a short bit on the powers-that-be, be they supernatural or temporal. They're probably at war with one another, so you could explain why this is the case.
2) Alternatively, you could take your generic fantasy and mix in a twist of something else to create a new setting. I
offered some suggestions on this before, and undoubtedly you can come up with others.
Either way, you'll have something to show to prospective players. I can highly recommend adding bits of "flavor" to your game as well - excerpts from stories that could be played out with your game, to create the right mood. World of Darkness does this very excellently.
Hope this is useful. Personally, without this addition or something similar, I'd probably buy your game if I ran into it and the artwork was good. But I'd buy it expecting a card game, not an RPG.
(P.S. I sent you a couple of PMs as well over the past days. Due to my rejection anxiety, I'm forced to point this out to you as you have clearly not noticed them ;) )