NPCs don't typically have Talent Slots in the game. Some of the Organization and Nemesis cards do, but I don't recommend restricting yourself (as GM) to only those frameworks. Adding one NPC Social Talent to any given NPC won't break anything, and will feel about on par with the Talent options that PCs have. NPCs that are meant to be a major social obstacle, such as jaded nobles, might have 2 or even 3 Social Talents, but this should be fairly rare just to keep it in line with the limitations players face re: Talents.
These cards are intended to "spice up" Social Encounters in Warhammer 3rd, helping to bring a little depth and variation to your social conflicts. Feel free to print these for your personal use, and please let me know if you find them helpful.
Several of those cards alter the difficulty of certain social skill rolls, such as the one that raises the difficulty of Charm and Guile while simultaneously lowering the difficulty of Leadership checks. The idea there is to mix things up a bit so the PCs can't just rely on a single skill for every situation. When I ran these, I tended to keep the cards hidden because as GM I like to be mysterious. In retrospect, though, it's probably better to point those cards out to the PCs early in the scene, to encourage them to swap tactics. Otherwise, you'll find the same high-Fellowship character attempting to power through using the same Skill again and again, and they'll completely miss your attempt at adding depth to the scene. My recommendation now is that you read the card out loud to the players the first time (in any scene) where the card is modifying a die roll. Preserving a sense of mystery is all well and good, but you need to give the players enough data for them to make meaningful decisions at least starting with the second attempt to influence any given NPC.
Some of the Talents are designed to slow down Social Encounters or discourage the PCs from ganging up en masse and overwhelming the NPCs by sheer volume of low-quality die rolls. Those are especially good cards to use if there's only one NPC in a scene, as otherwise the rules as written favor the brute-force approach to group Charm checks.
The cards above were made with the Strange Eons program. I've got a few dozen more (non-Social) NPC Talents sitting around on my hard drive, and hopefully I'll find time to post them soon.