[@Rogue Colm]

I think it all depends on the route you want to go. If you want to use DnD's system but have an overall fire-emblem sort of flavour that's one way to work things (and probably the easiest/simplest), the other route is to homebrew rules with [url=http://www.sjgames.com/gurps/]GURPS[/url] or something, which might prove a tad bit harder.