There is a general disconnect between what people are considering as "leader." Leader only means to lead, to be at the front of a line, setting an example. You can be a leader and have absolutely no sway over other people. So here's a breakdown of leadership. If this turns out to be a successful post I'll make a thread out of it.
Leading: Setting an example, front of the pack. Not necessarily the best, just in front. This applies to whomever has the strongest grasp upon a particular function. If the following information makes sense (Ti) and the forum agrees to it, then I am a "leader" in the area of Ti. You can lead with any function, but not have it be your main function.
Persuasion: Ability to influence people to bend to your will, usually by perception (Fe) People follow you because they are "moved" to emotionally. Many riots have Fe leaders. Hitler was a famous Fe leader. That female teacher in your class who's flaming ovaries can set ablaze all the established patriarchal culture, make some students cry, and yells for no apparent reason is an Fe.
Command: The ability to impose your will upon people using indirect threat (Se) People follow you because they will get hurt if they do not. Many front line military commanders are Se, ideally an ESTP who have Ti as a second function and leave the ethics for their nation to decide. Se as a leading function also allows for a more controlled body mechanics (S types are generally better athletes) Alexander the Great may have been an ESTP instead of the commonly mispercieved ENTJ. He fought on the front lines sometimes so far ahead of his own company that his own men he would be surrounded by the enemy
Resource Management: The ability to use logic to allocate resources in an environment (Te) People follow you because they either understand that your logic, or because you pay Se/Fe types to make them use their abilities to do the same. Te is about efficiency and effectiveness. Bringing order to chaos. The world is in a constant state of flux and chaos and therefore a properly developed Te leader can bring the world back from the brink of destruction. A war can be won without firing a single shot. Romans were experts at logistics but bad at tactics, hence their loss to Germanic tribes.
Control: The ability to understand the inner workings of prebuilt systems and interfaces.(Ti) A computer is a system, and understanding how it works allows people to control them. Leading in Ti has many strange effects. Ti knowledge of anatomy (doctors), psychology(obviously psychiatrists, torturers, socionists) computers(Hollywood hackers).
Pro-Action: The ability to predict future events based on past events, as well as the ability to see through distortions in the real world. This one is obvious, prophets are usually "enlightened" having both Ni and Ne at their disposal. Anyone who can predict the future or simply perceive a current problem can in a sense "lead" people and this has usually been the case. In order for many dictators to maintain corrupt control they must suppress understanding (Ti) an propagate lies i.e. propaganda (snuffing out Ni) and either promise people something (Ne) or make sure they are aware that they have no hope (negative Ne)
Duty: Difficult to add an adjective to this one. Fi are people who accomplish their "duty" Usually imposed using Fe. Can be imposed using Se as well but most countries have already abolished slavery. Duty imposed by Te can have corporate qualities. Leading Fi would be someone completing what they promised to do regardless of the illogic of it. From Le Petit Prince the torch bearer who had to continue lighting and extinguishing the lamp even though the speed of his planet's rotation increased to a full rotation every minute.
Imagination: Another difficult adjective, this time for Ne. Imagine being inside Joker's mind, its an MC Escher sketch of nuttiness, or a children's book with an ass pull ending. Where no amount of duty, understanding, anger or force really mean anything because the universe exists in a micro cosm. The only people who will make it out are the ones who can use the twisted logic. E.g. "I was stuck in a room made of 6 sides of blackboard and had a magical piece of chalk that never ended. It was my nightmare, math for all eternity. Then I had an idea, I broke the piece of chalk in half, and put the two halves back together to make a whole, and put that hole on the wall thus allowing me to escape through it." Seeing a potential in something even with complete lack of Ti/Te. This however, is much more difficult to discuss because Ne never actually invents anything new, it simply discovers what is already there and simply unused. Really I just hate Ne types who can't leave things well enough alone.
Relaxation: Another non-leading function. Si get people to relax. By most common definitions the opposite of "leading" It gets people to not do things. Leading in Si allows people to calm other people or else relax them. A massage therapist can lead a person to a better state of Si. Si can also be used for torture. Which is what makes NT types harder to break. Si as a leader function (not leading, but the ability to lead with an SI) would be mandatory for any spa resorts, or yoga or hippie smoky, druggy dens of villainy.
At some point I got bored of writing this article so if you have complaints about the second half go lead with your Si function and perform urethral milking on an equine.