xml:

		<item font="Times New Roman,10,1,0,0,0" left="40" top="44" right="182" bottom="48" align="0" border="0">
			<txt xpath="@ф"> </txt>
			<txt xpath="@и"> </txt>
			<txt xpath="@о"> </txt>
		</item>

TextBlock:

<TextBlock Text="{Binding Path=InnerXml, Converter={StaticResource stringConverter}}">

stringConverter:

        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            string strVal = "<a>"+(string)value+"</a>";
            XmlDocument xDoc = new XmlDocument();
            xDoc.LoadXml(strVal);

            string s = String.Empty;
            foreach (XmlElement xL in xDoc.DocumentElement.SelectNodes("txt"))
                s = s + xL.InnerText + xL.GetAttribute("xpath");

            string res = s.Replace("+br+", "\r\n");
            return res;
        }

            <DataGrid x:Name="txtGrid"
                      DataContext="{Binding ElementName=tvwNodes, Path=SelectedItem}"
                      ItemsSource="{Binding XPath=txt, Mode=TwoWay}"
                      AutoGenerateColumns="False">
                <DataGrid.Columns>
                    <DataGridTextColumn Header="xpath" Binding="{Binding XPath=@xpath, Path=Value, Mode=TwoWay}" Width="40" CanUserReorder="False" />
                    <DataGridTextColumn Header="&lt;текст&gt;" Binding="{Binding Path=InnerText, Mode=TwoWay}" Width="1*" CanUserReorder="False" />
                </DataGrid.Columns>
            </DataGrid>

<TextBlock Text="{Binding XPath=., Path=InnerXml, Converter={StaticResource stringConverter}}">