Summary: Paul wanted to encourage church leaders to continue serving faithfully after he's gone. We who lead live out what we've learned. As witnesses to the truth, we apply the wisdom we've acquired through experience and by time spent in prayer.
As General George Patton was preparing for combat operations in North Africa during WWII, he called on his aging mentor, General John J. Pershing, at Walter Reed Army Medical Center. Patton thanked Pershing for giving him his start as a Company Commander. Pershing said, “I can always pick a fighting man, and God knows there are few of them. I am happy they are sending you to the front; I hope they give you a free hand.” Before Patton left, he knelt down on one knee, kissed Pershing's hand, and asked for the General's blessing. Pershing said, “God bless you George, and give you victory.” Patton stood up, saluted, and left.
In Acts 20 (quickview)  the Apostle Paul addresses the leadership of the church of Ephesus, knowing this was likely to be the last time they would see him. He gives them his blessing in verse 32: “Now I commit you to God and to the word of His grace, which can build you up and give you an inheritance among all those who are sanctified.”
Paul wanted to encourage these leaders to continue serving faithfully after he's gone. God may change His workers, but the work goes on. In the military I learned that every soldier is expendable, no matter their rank or position; none of us are mission-essential. That's especially true in the church. When churches are built upon the personality of their leaders, they collapse when there's a change in leadership. Paul points out that Christ--the Head of His church--works through His servants, who simply make themselves available. We who lead live out what we've learned. As witnesses to the truth, we apply the wisdom we've acquired through experience and by time spent in prayer and contemplation.
Paul gives his blessing to leaders, and he wants us to bless them as well. He urges in I Timothy 2:1 (quickview)  that prayers be made in behalf of everyone in authority. This includes work, government, the church...any organization where responsible people make things happen.
Paul urges leaders to “be shepherds” within the church, verse 27. They're to keep watch and warn against false teachings that distort sound doctrine. God will equip His leaders in the task of building up the church. It is important that pastors know both the truth and the many untruths that are widespread. There are minor doctrinal differences (which we can agree-to-disagree on), but then there are falsehoods that can infect the church and lead people astray. We see this in the rise of cults that deny the deity of Christ, that publish other writings as divine, and claim to be the only true believers. We also see this in churches that deny the authority of Scripture and reject whatever they dislike in the Bible.
Paul says in his blessing of leaders: “I commit you to God.” He is entrusting them to God's care. Pastoral care is about developing relationships of guidance with compassion. Pastors are not to be remote but involved, closely connected to their congregations, and active in their communities. Henri Nouwen observed, “My understanding of ministry is simply living with the people, as the people.” Paul wants God to bless this work, and it must be done with integrity. Thomas Jefferson said, “God grant that men of principle shall be our principle men.” Only God can build us up to do this.