I would like what is essentially halfway between a Textarea field and a WYSIWYG field.

It would be the Textarea field in all aspects, except it would also have very simple format controls, like bold, italic, list items, and link.

Use case: A client has a heading with one word that is a different colour/font/size/etc. At the moment, our options are using HTML in a text field, or using the basic version of the WYSIWYG field. We don't want to make it too complicated for clients by forcing them to use the HTML code, and the WYSIWYG field takes up a lot of space for what is usually no more than a couple of words.