How can I improve the social / mental combat system in Vampire: Requiem?

The Storytelling System has balanced traits, with power, finesse, and resistance attributes and skills for the physical, social and mental traits.

Still, until recently only physical combat was described, letting the social and mental ones fall on the shoulders of the storyteller and players. (Requiem for Rome and WoD: Mirrors recently introduced social/mental combat, but see below for the problems with them.)

This had at the very least the following consequences:

  1. A player with easy social/mental skills could shine while role-playing or solving puzzles despite the low social/mental skills of his character
  2. On the opposed side, a player with average-to-low social/mental skills would never be able to really play Mata Hari or Sherlock Holmes, despite having maxed out his social/mental skills
  3. Thus, it is more profitable to invest experience in physical combat skills – there, one is sure experience will be efficiently used, where in social/mental skills the points’ contribution is unsure at best
  4. Conclusion: You end up with combat-skilled characters

This happened to our group, because:

  1. Our mental challenges (i.e. investigation, puzzles, etc.) were failed or missed by the players. (Not to mention hours of useless and boring discussion to decide the course of action, which killed both the pace and the mood of sessions…)
  2. As everything social was “discussed” and not standardized, players could ignore anything that didn’t please them

The problem is we’re playing Vampire: The Requiem, and half the interactions between important the PCs and other vampires are simply social – Elysium stuff, etc.

So we (the two storytellers for our group of 6 people) are trying to bring social/mental combat mechanics into our games. Our first experiments were interesting (players were to throw dice to investigate), but we are still working on it.

My question is: Have you devised systems for the Storytelling System* for social and mental combat?

There are mental/social combat rules in Requiem for Rome (mostly rhetoric and reason debates) and in World of Darkness: Mirrors (Sway for generic social combat; and Anticipation, Setup and Declaration for mental “special effects”), but I’m looking for alternatives that merge everything interesting together. (For example, half of the rules for Sway are interesting, but the need for a simple roll and simple success is too easy for a “combat”.)

* Though we’re playing Storyteller System, answers for other systems (D&D, Shadowrun, etc.) would be interesting, too.