A deacon did Benediction at our parish today (full-fledged, cope and all.) Is that legitimate?
Yes, in the Latin Church deacons, transitional or permanent, can preside at, give, Benediction of the Blessed Sacrament. They dress in their choir dress (cassock, surplice) surmounted by a diaconal stole an cope. A biretta would be used to come to the sanctuary of the Blessed Sacrament is not already exposed, and to leave the sanctuary.