The XML IDE ... modeling, editing, transforming, and debugging XML-related technologies, including an awesome graphical schema designer, code generation tools, file converters, debuggers, profilers, database integration, and explicit support for XSLT, XPath, XQuery, WSDL, SOAP, and Office Open XML (OOXML) documents. It even included Visual Studio and Eclipse plug-ins...
A nice commecrial XML editor that not only has excellent validation, xslt and xpath and xquery, andformatting objects (fo) features, but supports an XML data grid view and XML Diff & Merge! It even supports generating SVG graphics via XSL transforms on data files, remote editing over FTP or WebDav, and is available as an Eclipse plugin. Only $48 for Academic use.