It seems to me that some have the opinion that blessing is an act reserved to the ordained. Fr. John Dietzen who is a Catholic News Service columnist writes that there are two books of blessings that can be used by the laity. Catholic Household Blessings and Prayers published by the U.S. Conference of Catholic Bishop’s Committee on the Liturgy and Book of Blessings (Roman Ritual) also available from USCCB Publishing at 1-800-235-8722. All sorts of blessings for many occasions and purposes are listed in these books. I don’t think that any explicitly for use by EMHC’s at Mass are included although Dietzen does support the use of the “Hitler Salute” type of arm extension joining the priest in blessing certain groups at Church functions.
Blessings within the context of liturgy are reserved to the Ordained. A general statement that Blessings are reserved to the Ordained would be misleading.