A blessing was a statement that was believed to bestow divine favor or wished one well.
One of the duties (if requested) of the Emissary was to bestow a marriage blessing on newly married Bajorans. In 2372, Vedek Porta brought a couple to be blessed by Benjamin Sisko. When Kira Nerys stepped out of Sisko's office to get the couple, Jadzia Dax asked if he remembered the words. Sisko replied, "I hope so". He was able to carry out the action perfectly. Afterwards, Jadzia commented that his role wasn't that bad.
Contemplating being replaced by Akorem Laan, who believed he was the Emissary, Sisko enjoyed the prospect of shedding his religious role, as he would not have to give any blessings or do anything else of that nature again. This ultimately did not pan out.