What would it be. Precisely like quests, weapons, lore, characters or even the unreasonably absurd (guns, multiplayer, etc.)
Be as specific or vague, if you prefer, as as you like. I'm curious what your hypothetical responses are.
--- Me, personally, I'd like to see Goldbrand. Maybe with the enchantment (Fire damage 30, shout cooldown reduced 20%)? There's a serious lack of useable Rp items, and a sword allegedly forged by dragons is just too Dovahkiin-ish to not be in Skyrim.