I just tried to edit this question about editing etiquette. Well, I could easily enter the editing page, do my edits and check with the preview that everything was OK. But on submission I got the message
Oops! Your edit couldn't be submitted because: 'discussion faq etiquette editing' contains a tag reserved for moderator use
This is somewhat annoying: Why didn't the system tell me in advance, when I hit the edit link, that I can't edit the post anyway? It would be very nice if this could be implemented. By the way, this was already the second time that it happened to me; the first time was when I tried to edit this question after the tag status-bydesign had been added.
So much for the feature-request, let me add the question: For the question about editing etiquette, do you think it's OK that only moderators can edit it? I think yes, since this is really an important faq entry and not a question.