oXygen XML Author, a simple-to-use yet powerful tool that will fit into all your visual XML editing needs.
The perfect tool enhanced with cross platform interface, helps visual XML editing work simpler. The perfect visual XML editor supports CSS style sheets with specializations for DITA, DocBook 4 and 5, TEI P4 and P5, XHTML. It also includes support for document templates useful for creating new xml instances, CSS for WYSIWYG like editing, interface actions for creating and editing lists, tables and marking up specific content, XML Catalogs for faster access to resources, schema files for validation, transformation scenarios to convert from XML to HTML and/or PDF. It also supports: the DITA Manager, toolbar for editing, navigation links support, a tooltip combined with the marks from the XML outliner and with the location bar, various levels of display for XML element tags, and so on.
This must have tool also includes the spell checking, validation, search and replace, XPath execution, and so on.