I own an 8th - 9th century AD Byzantine reliquary cross with Christ on
the front
withh outstreached arms- there is a halo above - crown - and I believe
sun & moon. On the reverse it is pain and flat except for a line cross
etched on the cross member than the letters KE BONOE . Can you
translate that for me and advise what the symbols means. Thanks

I do not feel fully qualified to provide a definitive answer to your
interesting question, but here are a few of my thoughts.

"KE BONOE" may be a medieval Italian phrase that would roughly
translate as "HOW GOOD" or "SO GOOD" (referring to the unsullied
goodness of Christ.) The modern Italian equivalent would be "che
buono." This could indicate that your Byzantine cross is Italian in
origin (many Byzantine religious objects do have Italy as their
source, even though most of us don't initially think of Italy when we
see such artifacts.)

Regarding the symbols, the halo is a symbolic element that predates
Christianity; its use initially signified royalty. A halo was depicted
instead of (or sometimes in addition to) a crown; both the halo and
the crown were emblems of lordship. Early Christian artists adopted
the halo symbol as a way to illustrate a nimbus of Divine light which
emanates from within a holy person or, as in this case, from Christ
himself.

The sun and moon are references to Scripture, notably Joel 2:31, "The
sun hid its light and the moon turned to blood." Christians believe
this Old Testament verse to be a prophecy of the darkness that fell
upon the land during Christ's sufferings on the cross at Golgotha.

I am an amateur in these matters, and most of my knowledge comes from
my studies in the history of the Church, not from the world of art
scholarship, but I hope some of what I've said is useful to you.

It would be probably very helpful to us if you could post a digital
image of your cross. If you have access to a digital camera, or if you
can scan a photograph for us, and post it on the 'Net where we can
examine it, this would be of great assistance.

Best wishes,
pinkfreud

Possibly "KE" is an abbreviation for "Kyrie" - "man, young man" -
often used to refer to Christ, especially in that segment of the sung
mass known as the "Kyrie eleison".

It could well be that KE is an abbreviation for the Greek words Kyrie
Eleison: 'Lord, have mercy'.
But I wonder what the capital "E"s look like.  Capital S (sigma) in
Greek looks similar to a capital E, a little like an M turned on its
side.  The other letters on your cross would be much the same whether
it's Latin, Greek or Italian.

This is a long shot, but could the 'BONOE' part possibly be read
'OYNOE' (with the final 'E' being a capital sigma as described by leli
above)? This would be the standard Byzantine Greek abbreviation for
'ouranos', which means 'heaven' - as listed here:

Byzantium: Greek Abbreviations
http://www.fordham.edu/halsall/ikon/greekabb.html

It would help if you could scan in the writing (or copy them by eye &
hand onto a piece of paper and scan that in) in case the script is not
Latin but Greek.