The hand of Christ shown in icons with crossed fingers is raised in blessing: “the fingers spell out spell out “IC XC”, a widely used four letter abbreviation of the Greek for Jesus (IHCOYC) Christ (XPICTOC)” – from this lovely blog: A Reader’s Guide to Orthodox Icons.
Christ Pantocrator from Haghia Sophia, Istanbul
I was wondering about whether this is partly why we cross our fingers for luck. Where I grew up, it was ‘unlucky’ to cross the fingers of both hands. I have no idea why.
Image rights here
Meadowsweet 
I love icons and really get into the gestures and all the details, but I never made the association with crossing fingers before. I was told we crossed fingers, because well, it made a cross.
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Yes, granted! I just don’t know why we kids made up the additional rule not to cross the fingers of both hands: there was some work done on regional variation in skipping games/rhymes, local ‘rules’ etcetera…I’ll have to look it up. Thanks for your comment, Biltrix
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