<?xml version="1.0"?>
<XPath xmlns:bar="http://example.org/bar" xmlns:baz="http://example.org/baz" xmlns:foo="http://example.org/foo" xml:lang="en-ie">
    (//. | //@* | //namespace::*) 
    [ 
              <!-- only namespace nodes -->
              ancestor-or-self::bar:Something  and
              (count(parent::node()/namespace::*)  =
               count(parent::node()/namespace::* | self::node()))
    ]
</XPath>