An easy-to-use open source WYSIWYG XML editor

Serna Free
Free
Offline
http://sourceforge.net/projects/sernafree/?source=navbar

Serna Free XML editor is an easy-to-use open source WYSIWYG XML editor for those who wish to smoothly adopt the XML technology. Indeed, Serna Free is the most powerful among free and open source XML editors for WYSIWYG authoring.