Bushi, I also have an Iksar that likes factioning - it's pretty much necessary if you want to do the old world city quests for any reason. Yeah, there's always illusion potions, but they're expensive and not always available.
Maoukiji, the best reason for non-residents raising this faction, imo, is that you can sell to the dark elf merchants in South Ro. If you're farming the nearby sand giant elite's for plat, it's a cinch to run down the hill and sell all that heavy fine steel to the dark elves. It's an especially slow trip to other merchants if you're encumbered with all kinds of heavy swag you grabbed off the giants. Being "ally" faction with the DE's certainly helps get the best prices, too.
Bushi, if you can't get the quest Npc to take the wine, you can just take a dark elf illusion potion you bought from the bazaar (safe, but expensive way), or shroud up as a goblin rogue, buy a few invis potions for getting through neriak, and SNEAK behind the npc in 3rd gate, and try the hand-in that way (more dangerous, but not as expensive method). No need to initiate speech - just start handing the wine in. Don't hail him either - or he'll turn and you'll not be able to do the turn-in.
If you're interested in more Neriak factioning for convenience and safety reasons, then you will also want to do the letter quest that starts in east Freeport by hailing Zvarina Zexus (sp?) and completing this quest ONCE should make you non-kos to the clerics of Neriak 3rd Gate. You'll need a DE illusion potion before you hail Zvarina, and also when you do the turn-in in Neriak 3rd Gate. Sneaking won't cut it here.
Also, you'll want to turn in tons of rat whiskers to the exterminator in 3rd gate as well, which will make you non-kos to the Indigo Brotherhood, which *some* (Commons and Foreign Quarter district) Neriak guards are on. About one full backpack should do the trick, depends on how bad your faction is. Best place to farm them is the "rat den" area in the Warrens on Odus (they have almost instant respawn time).
Finally, con the female DE's on top of the bridge when you're standing at the entrance to Neriak Foreign Quarter - you should just be able to make them out from there. If they con threatening, and they likely will, you'll need to kill the high-elf spellcasters in Nektulos Forest, near the hill close to the PoK portal. They'll be over by the wall. It's likely you passed them on your way to Neriak. They give a nice bonus for "The Dead" faction, which is the Shadowknights and Necromancers of Neriak. Keep in mind that the ghouls in the "lobby" outside the Necro guild will always be kos to you (actually, all non-darkelves).
There are a few other factions in Neriak, like the rogues guild, but the factions mentioned above should keep you pretty cozy while in town.
Hope this helped.
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If you can't do something well, learn to enjoy doing it poorly.
My Rathe / Prexus characters:
Bigbronze Bloodyaxe, 62 Ogre Berserker
Verbeeg Bearfang, 62 Ogre Beastlord
Glabrezu Spiritcaller, 62 Ogre Shaman
Zirumkin Zenomorph, 62 Gnome Wizard
Korgulon Soulwraith, 76 Ogre Shadowknight <Shining Alliance>
Incarnadine Summoner, 65 Drakkin Magician
Bristlebane characters:
Zalkahriz Ebonscale, 64 Iksar Necromancer
Gnomorre Gniceguy, 55 Gnome Rogue
Whytfire Lonewolf, 55 Woodelf Ranger