I don't know for sure at which point a sacrament is effective, but I think some of the posts above that discuss the process, such as the Proskomidi (Preparation) service being an important aspect of the Preparation of Holy Communion, as is the Consecration, are probably more to the point than a specific action.
A young priest who thought that the joining of the hands was the moment that the Sacrament (Mystery) of Holy Matrimony is effectuated, asked his bishop his opinion. The bishop replied, the Sacrament of Holy Matrimony is a continuous process, from the beginning of the service, "Blessed is our God..." to the conclusion "Through the prayers..," when the mystery of the sacrament is effective. (This reminds me of the Western practice, "I now pronounce you husband and wife," sometimes done by Orthodox clergy, is consistant with the bishop's explanation indicated herein, except for the "I" being inconsistent with Orthodox teaching.)
A few comments about practices I've seen noted above, my experience being from the GOAA:
At the conclusion of the Funeral Service, the deceased is anointed with oil by the priest in the form of the cross, upon the chest, "Sprinkle me with hyssop and I shall be cleansed, wash me and I shall be whiter than snow;" having previously been sprinkled in the form of the cross with dirt (ground), "Earth thou art and to Earth thou shall return."
In the Sacrament of Holy Confession, the priest places his stole over the penitent's head, who is kneeling, when reading the prayer of absolution. As to the "breathing," it could be on his own initiative, a priest, suspecting demonic influence, breathes as he does during the Baptism, "Expel from him/her every evil and impure spirit hiding and lurking in his/her heart (3);" just my own guess, not a practice during Confession I've ever seen.