Well, sorry to burst your bubble, but a divine diplomat (and especially the half-elf travel/war build) is pretty cliche, from a purely mechanical point of view. The background might be a little more extravagant, but when you're asking in the rules forum I suspect you want some teeny-tiny technical differences, too, right?
Your party has pure divine and arcane spellcasters, so multi-classing might be an attractive option. This way you don't infringe on the territory of another player and can follow some concepts that might be less than wise from a pure power-slinging point of view...
And obvious combination would be combining Ranger with Cleric. Take a deity with a more esoteric, scholarly territory and you could play one of the few practical followers, the Indiana Jones type of scholar. Knowledge, Travel...
Or maybe a Monk, if the dwarf won't mind and the DM lifts the restriction on multi-classing. Searching for new prospective students, looking for the ancient scrolls of W'at-D'no, or just trying to find the perfect human being. Could be very diplomatic and polite, the martial arts wouldn't be at the forefront. In a combat you'd be a nice support on all fronts, and with some good buffs might even shine...
Rogue/Cleric is something you don't see that much, especially when you avoid heavy armor and weapons. Gods of trickery and luck can provoke all kinds of strange quests. Or a seductive secret agent from the Temple of the God(ess) of Love. Yay
For the really strange, take a Half-Orc Seeker of the Eye (no luck looking that up). See ('cuse the pun), since the time when Corellon took the Eye of Gruumsh, the orcish race is on a steep decline, the wound-induced rage of the prime god blinding any higher pursuits the race might be capable of. So there's the exceptionally intelligent half-orc who wants to seek what's lost. Mechanically the Int and Cha penalties are tough, but who expects a eloquent half-orc?
Thought about a paladin? There are other options than the stereotypical shining crusader. Maybe you're the chronicler of the war, not looking for battlefield statistics and epic songs, but for the light of human soul in troubled times...
