[quote="Aramis, post:11, topic:195804"]
It's the position used for blessings by priests and bishops in the Byzantine Rite*, and in some of the other Eastern Christian Rites; it's fallen from use in the Roman Rite.
From the priest's view, it forms I C & X, the letters in the greek and slavic abbreviations IC XC for Jesus Christ (Iesus Christos)
*Some groups have different hand postures, specifically Old Believers
It is also the way that Orthodox bless from priest up, not just bishops.