Hi,
For the first command sed that not work in ksh script, try as:

Code:

sed -i "s/${SEPARATOR}\$//g" file_name

But, maybe not work again, what is $SEPARATOR ?

How to launch your ksh script ?

For information, accented character may not be in sed. these depend your locale.

EDIT: try as:
1- how to find octal value of character:
In my example, my text in File is FOOàBAR.

Code:

$ cat File
FOOàBAR
$ sed -n 'l160' file
FOO\303\240BAR$

Here, I see that character "à" is in octal \303\240 but really value is \0303\0240.
And to replace "à" by nothing:

Code:

$ sed  $(echo -e 's/\0303\0240//g') File
FOOBAR

Regards.