I love social specialists in RPGs, and I would love to make a party leader who had real leadership abilities.
I keep thinking back to my fantastic character in Arcanum, a well-bred lady who went about in a fine purple dress. Her magical abilities were minor, but adequate to justify her place in an adventuring group. Her main "power" was her great personality which allowed her to lead a large team of more rough-and-tumble companions. (The companions in Arcanum were wonderful, weren't they?)
That character was possible because of Arcanum's classless system. I would love to be able to do a character like that again in Project Eternity, even if Charisma or whatever has no effect on your party size. Hence, I suggest the Nobleman class.
What would such a profession look like in terms of abilities? He would be likely to have at least some magical skill, being well-educated, but would certainly not be as powerful as a specialist. The spells he would naturally study might be utilitarian, informational, or cosmetic rather than destructive or combative. He might be trained in the use of dueling type weapons and light armor. He would excel in "formal", one-on-one combat, but might be less effective in large scale brawls. Social skills would be his true fort