This relates to issues CONF-1339.

If attachments can be viewed via WebDAV then it is possible to edit them directly from Word, Excel. If confluence could allow the user to open an attachment from the DAV server rather than downloading it and opening from a local temp folder then the user could save the attachment back to the server automatically by hitting "Save" in word.

If confluence is proxying the WebDAV requests then it should be able to apply standard confluence permissions to the DAV PUT command.