I don't intend to try to write a book about the title (it would take several books), and I will only share according to the Grace that God gives me in order not to be led off focus (because I certainly know only a little). May God add Grace to this for Light and revelation to those who read. Amen.
There are many, many articles online about the apostolic ministry and the apostle. Some are in error, some are true, but none is complete by itself (and so the Church needs every part and piece). Paul Oyarenua writes in part:
"Another issue of functional grace of the Apostolic is carrying out the great commission. Apostolic grace is for the growth, expansion, enlargement and increase of the kingdom of God. Apostolic grace is meant to advance the kingdom. The Apostolic grace is to cause increase of the church. When I am talking of increase, I mean a healthy church. Not what we see today all over the earth. A healthy church is a balanced Church. One more function of the grace of God is that Apostolic grace is for building the body. God is against us building empires and kingdoms for ourselves. He pulls down the first and scattered the people over the earth. His primary purpose is to see a church healthy enough to accommodate His principles and revelations. Apostolic grace is meant to raise sons and daughters and expose them for the work of the kingdom. I am not referring to opening of Bible schools but bringing up sons and daughters in the kingdom through mental renovation and intellectual balancing" (http://www.identitynetwork.net/apps/articles/default.asp?articleid=59646&columnid=).
When I say 'apostle', I speak only of the true God-called and 'activated' apostle, not those who say they are apostles and are not. The apostle causes favor to be drawn to the Church and brings Grace for unity in every measure among the saints. Because of the Grace on his life, an apostle can walk into a bad or hopeless situation, and the Lord in him will bring blessing and hope. Because this ministry office is so incredibly 'weighed-down' with Grace (power, abilities, talents, skills, wisdom, the authority to release people into their destinies, etc.). satan resists it more than he does the prophet and the others.
But not only apostles can have apostolic Grace. One of the workings of apostolic Grace is that it unveils what is hidden, uncovers what is kept secret, shines light on what hides in the dark. This is the total opposite of satan's M.O., therefore, again, apostles and apostolic people are singled out by him for especially more affliction, hardship, and suffering. Another apostolic Grace is the ability to bring God's wisdom and strategy into situations; this spells the end for satan's little-disputed works whose tactics are all defeated by God's strategies and weapons (once we know both). These are ways in which Jesus manifests in apostles and the apostolic. Needless to say, the true apostle and apostolic poses a very real threat to satan's kingdom, because the government of God is on the shoulders of the apostle, and God's authority goes with them. We see what this government looks like in Jesus when He came to earth: "And the government <of God> will be upon His shoulders" (Isa. 9:6). This <apostolic> government can be called 'the say-so of God'; that means God gives apostles the power to "decree a thing" and have it established. (Job 22:28.) Prophets also have this Grace, but they are different; moreover, I am focusing on the apostle at this time.