In my experience, the Roman glass is not appreciably more brittle
than regular glass (not tempered glass or “pyrex” of course). Some
of the shards can be quite thin and will certainly be very fragile as
I believe the comment about “flaking off” is a concern for the loss
of the loose, friable layers of patina that are present on some
pieces. This beautiful iridescent material is subject to flaking off
with bumps or abrasion. Some manufacturers have said they actually
take the flakes that have fallen off and glue them back onto the
glass surface in the finished jewelry. Beautiful, but in my opinion
deceptive, unless disclosed.
Even the bare Roman glass exhibits an iridescent patina, though more
subtle than the silvery flakes just described. I’ve not observed
that this base patina will suffer from touch or the slight abrasion
of handling as the flaky patina will.
Hope this helps.