The Rogue is supposed to be an adventure that lives by hits wits more than his blade. The value of Wits is pretty much what many RPGs escalate towards. Hacking and Slashing isn't as savory when tactics and strategies employed allowed arrange the situation to give them the advantage.
Looking at intelligence or cunning, it is amazing how simply by re-arranging certain conditions something totally different comes out of it. In combat, imagine positioning where forces surround and divide players vs positions that allow the players to funnel weaker forces against more superior ones. In social and diplomatic puzzles, it is finding and converting a resource or leverage you have into something that can influence someone who can give you something in return.
My definition of Rogues are those who resolve problems with their witt and cunning, and not through direct violence. A kind of Rogue that exists in the real world are Courtiers, Brokers, Valets, Sergeants (another term for servant), Entrepreneurs, and Agents. More specifically, I want to simplify on the concept of the Agent: someone who looks after the his master or patron's interests because his own are rewarded by doing so.
The kinds of Rogues I've mentioned before: Courtiers, Valets, Brokers, etc. are all kinds and forms of agents. They represent the interests of parties more powerful than themselves. A courtier represents his Lord, the Arch Bishop or Patriarch, A Merchant Prince, the Guilde, A far flung kingdom etc.. Valets, and Sergeants represent powerful individuals when their presence needs to manifest indirectly in the events these agents oversee.
So what is it that people look for in representation: Judgement or the ability to know what is best for their master/employer/patron. Even in real life, among employees, comrades and peers our representative must be the one with the best presence of mind to see that things occur in a particular way.
Like the diplomacy I'd like to break this down to something simpler and easier to digest. The first set of skills are those that involve information gathering. This is the most basic agent. Spies, Scouts, Representatives, Diplomats, Scribes, and Couriers all come back or send information to their masters.
2 fundamental Skills: Observation and Writing. the most basic is to Perceive and the be able to communicate it accurately and in detail. Assume Language is a prerequisite.
Next group of skills deal with Information gathering into greater depth: Research, Body Language, Psychology, Detect Lies, Interview/Interrogation, Administration (Bureaucracy), Accounting, Merchantile (analyzing basic economic condition), Military Intelligence.
All these skills, will be useless if there was no way to communicate it readily and effectively to the parties concerned. Of course useful set of skills are: Languages, Cryptography (ciphering information), Holdout (hiding and disguising information), Slight of Hand, etc...
Pushing. Above, intelligence gathering is useful but very difficult to use when information has a short expiration date. In courts, marketplaces, empty hallways of the palace, parties, and bedchambers Agents primarily push. They make things happen in a way that is advantageous to his master. One thing is to react, which requires information to address such an appropriate action the other and more simpler course of action is to CAUSE an Action.
Take away the daily reports and the meticulous details, a highly skilled Agent PUSHES his masters agenda. He courts the right people, puts into the air the right kind of information, and manipulates the information environment to be a certain way, so as the subjects to act a certain way.
Pushing Skills: Public Speaking (Oration or Storytelling), Acting- playing a role, Persuasion (Pushing the right buttons, framing information in a way the audience is most receptive), Arguing (Diplomacy, Philosophy, theology, Law skill in GURPS), writing,
These skills all serve to push, while the more complex information gathering skills point to WHERE to push. Use Religious Righteousness to push a cause, Play to the Weakness of the Lord, be it his Pride, Envy, Fear, Lust, Greed, Vanity etc, Play to the Crowd's Desires: demonizing a foe or people, make them see themselves as liberators, civilizers, and bringers of justice. Play to the self-interest manifesting as altruism.
The Agent Pushes the mark to act: to declare war, to wed, to spend, to tax, to punish, to build, to ostracize, to associate, to court, to move, etc... all towards what would be to the advantage of the Agent's master.
When I write my Agent Template, it will be a LONG and arbitrary list of builds designed to Push. there are tried and true strategies, but unlike other templates Agents are better when they build on their diverse background and strengths than to follow the most advantageous and traveled routes.