The blessing is the act of declaring God’s favour and goodness upon others. Throughout the Bible, we see that blessing is not only the good effect of words, it also has the power to bring them to pass. We can't consider that every blessing we pronounce will come to pass as if it were some mechanical formula. That’s up to the Lord. However, let’s not sell the action of blessing short either! The apostle John said that when we pray according to His will—and a blessing is a type of prayer—we can be sure that the Lord hears us and will give us what we’ve asked for (1 John 5:14–15). Thus, God responds to the words in our prayers of blessing.
Another way to think of a blessing is that we are asking the Lord to wrap up His people in His protective and loving care. We are asking the Lord to extend positive actions in the life of the one being blessed. We see this reflected in the Psalms: ”For You, O LORD, will bless the righteous; with favor, You will surround him as with a shield”(5:12). “Save Your people, and bless Your inheritance; shepherd them also, and bear them up forever” (28:9).
The blessing is the opposite of cursing. Eerdmans’ Bible Dictionary defines a curse as the “invocation of harm or injury upon a person (or people), either immediately or contingent upon particular circumstances.” Therefore, we are asking the Lord to extend a whole range of good things upon a person when we speak blessing on them.
A blessing is something we find throughout Scripture. We find for example St. Paul blessing St. Philemon with the words “The grace of the Lord Jesus Christ be with thy spirit.” (Philemon 1:25) It is essentially a prayer to the Lord for the spiritual and eternal well-being of the other person. In the Old Testament, we find father’s give their children their blessings (e.g. Abraham, Isaac, Israel..). The priests of the Old Testament were to bless the people with the words: “The Lord bless thee, and keep thee: The Lord make his face shine upon thee, and be gracious unto thee: The Lord lift up his countenance upon thee and give thee peace.” (Numbers 6:24-26)
Every Orthodox Priest was ordained by an Orthodox Bishop, every Orthodox Bishop was consecrated by a previously consecrated Orthodox Bishop back to the original Holy Apostles (known as Apostolic Succession) and every Apostle had direct contact with The Lord Jesus Christ Himself; therefore by kissing the Orthodox Priest’s hand, we have an unbroken physical and spiritual link to the True God-Man Jesus Christ Himself.
Do you know that the proper way to greet a priest or a bishop is to ask for his blessing and to kiss his right hand? How do you do this? Approach the priest or bishop with your right hand over your left hand and say, "Father (or Master, if it he is a bishop), bless." This is much more appropriate (and traditional) than shaking their hands. Remember that the priest and bishop are NOT just "one of the boys." When you kiss their hand you show respect for their office. As they give you a blessing, they will trace the sign of the cross on you, with their fingers held in a particular way that actually spells out the letters IC XC (which means Jesus Christ). So in actuality, he is imparting the name and grace of Jesus Christ, whom he represents, to you.
It is the priest and bishop who "offer the Holy Gifts" on your behalf and through whom the Holy Spirit blesses and sanctifies them and you. So the next time you greet your priest or bishop, don't shake hands or simply yell out hello, go and ask for a his blessing.