A leader must be able to tolerate stress and frustration well. A leader should also have power and be able to influence other people well and in the right direction. A leader should also be optimistic, enthusiastic and open towards his/her work and the people around them. Having a sense of duty, self-confidence, resiliency and a high standard of excellence are also very important traits of a good leader. Good leaders are also normally tough-minded and able to put himself/herself into other peoples' shoes.
Good leaders trust their own instincts when making decisions as reasoning and logic will not get you through all situations. Good leaders also remain alert and stay focused most of the time. Good leaders never rule others; they only empower others, and that is the reason to why they succeed in being good leaders.
I think a good leader remains calm under stressful situations so that they can think of ways to manage that crisis. A good leader also tries to be positive and have high hopes that in the end the crisis will be resolved. A good leader also considers the consequences of his actions before carrying them out. By stepping into other peoples' shoes, a good leader will also be able to find out how other people feels and thinks in the crisis.
Adapted from: http://www.smallbusinessnotes.com/managing-your-business/leadership-traits.html.