XML Notepad is an easy. lightweight, and convenient XML editor. Editing an XML file is not rocket science, and you don't need to have developer skills anymore to edit them. Don't be afraid!
Note: This is not a Swiss Army knife for XML. There is no overhead with XPath and all that stuff. This tool can open only well-formed XML, and it neither tells you what is wrong with the document nor repairs it. For that puprpose you will need an expensive "Swiss Army knife" tool. Just edit, rearrange nodes, or create new XML documents. That's it.