As a king, Jesus demonstrated his rule over creation through miracles while on earth, and today rules and reigns over his people through church leaders, principles, and systems by the Holy Spirit and according to his Word.
Kings excel at systems, policies, procedures, planning, team building, mission executing, and simply maximizing resources to accomplish measurable results.
The danger can be that a king can lead people into false doctrine and mere pragmatism. A king can burn his people out and use them for tasks without truly caring for them and seeking their spiritual growth.
Kings like charts, graphs, and checking things off from their to do lists.
The content of this post leans very heavily on the teaching of the folks in the following organizations: The Resurgence, The Gospel Coalition and Desiring God. Pastor Jamie Munson spoke on this topic awhile back … you can find the audio here: http://theresurgence.com/2010/12/13/prophet-priest-king