Charsi imbue can be any item dropped by anything. It's one of your "freebies". I intend to save mine for an ethereal PikeMeh Smith dropped me 2 claws....
One a failed set and the other a failed unique just for added lulz
Now erm do we have to have a SU drop whatever item we get Charsi to Imbue or can it be any item whatsoever be it dropped by something else or bought from a vendor? I would assume the later as SU's dropping non magical items is kinda rare