My instinct would be to use dired to assemble the list of files and then use the dired open file action, do the simple edit, save and close the buffer, which will return to the dired buffer again and go to the next file name all within an interactive macro. And then repeatedly execute the macro as it steps through each file.

Alternatively, manually assemble the list of files in a text buffer and use M-x ffap to open the file under the cursor, and do the same as above.

If this is something you will be doing frequently, then writing elisp may make sense, but you can get the elisp that a macro represents as well.

Start with an interactive macro.