PASSION: An effective leader is a person with a passion for a cause or someone with a dream and a vision that will better society, or at least, some portion of it. Also, without passion, a leader will not make the necessary courageous and difficult decisions and carry them into action. This is not to imply that all decisions are of this nature but you can be sure that some of them will be. A leader without  passion for a cause will duck.

HOLDER OF VALUES: Leadership implies values. A leader must have values that are life-giving to society. This implies values that are embedded in respect for others.
A leader can be of varying 'warmth and fuzziness,' but a leader has to respect others. You can’t lead without it. Respect ensures a smooth route to deal with diversity of persons.

VISION: This is a bit different from passion, but in other ways it isn’t separable. If one doesn’t care about a subject, an issue, a system, then one won’t spend time thinking about how it could or should be different. Yet, one could have strong feelings about something and not good ideas, particularly if one didn’t spend a good deal of time studying the topic. Thus a leader has to have some ideas about change, about how the future could be different.

CRETIVITY: One has to think out of the box to have good visions and to come up with effective strategies that will help advance the vision. I’d also add here the need for a sense of humor. It’s a creative skill that is in great need by leaders.

CONFIDENCE AND HUMILITY :While one can have a great vision and good ideas for change, and even passion for it, if one isn’t confident, then action will not occur. Without action, there is no change.
Yet, paradoxically, a leader needs to be humble. No matter how creative and bright one is, often  ideas might come from others too.

COMMUNICATION SKILLS:
None of the above assets will work for a leader if she can’t speak or write in a way to convince others that they should follow suit, join the team and get on board.

Thus,i would say that an effective leader has to have a purpose coupled with balanced personality, skills and knowledge to realize purpose fufillment.