Persuasion

This trait is, quite simply, the ability to get people to do what you want them to do.

This does not necessarily have to do with how one speaks or acts, but encompasses everything about how someone pulls others' strings. This comes in handy when trying to haggle for a better price on that nifty longsword/can opener, planting rumors, seducing the kings daughter, or trying to convince the king he'd be better off naming you as heir. The persuasive are great liars, negotiators, insult comics, and flirts.

Persuasive people are those such as used car salesmen, upper management, and con artists. Persuasion has many uses, some very nefarious. Adolf Hitler and Joseph Stalin were both Persuasive and convinced many to do terrible things.