Hide edit pencil for non-staff users

If you add a second bit to reset it for staff it should do the trick:

.topic-body .post-info.edits {
    display: none;
}

.staff .topic-body .post-info.edits {
    display: initial;
}

Though (FWIW) I actually still find it useful to know a post has been edited even if I can’t see the history.