Writing software is always a good idea, at least for the experience, so don't be offended by the following comment.
In the case of this particular itch, there are many small statically linked editors, some of them quite powerful. I don't think a small emacs was ever spotted, but the original vi (not vim) is often statically linked and present in /bin in Linux installs (it's a rescue thing).
Micromacs was favorite in the late 80s. JOVE early 90s. And the commercial unipress emacs. GNU emacs outlived them, probably because situations where a light spot editor was desired are now fast enough that there is very little additional cost to a full featured editor.
That being said, I still have EDITOR set to /usr/bin/emacsclient.
In the case of this particular itch, there are many small statically linked editors, some of them quite powerful. I don't think a small emacs was ever spotted, but the original vi (not vim) is often statically linked and present in /bin in Linux installs (it's a rescue thing).