The Pope is the visible head of the Church Militant and the Principal of Unity thereto. The Papacy is a supernaturally negatively protected juridical Office, as explicitly guaranteed by Our Lord and Savior Jesus Christ Himself in the Holy Gospel. Confirming the bretheren is a visible hallmark and ministry of the Petrine Munus (Office).
And the Lord said: Simon, Simon, behold Satan hath desired to have you, that he may sift you as wheat:
But I have prayed for thee, that thy faith fail not: and thou, being once converted, confirm thy brethren.
-Luke 22: 31-32