use strict;
use warnings;

use XML::DOM;

my $xml = <<"__EOI__";
<?xml version="1.0" encoding="UTF-8"?>
<TEST> \xC3\xA9 </TEST>
__EOI__

my $parser = new XML::DOM::Parser;
my $doc = $parser->parse($xml);

open my $fh, ">:utf8", "test.xml" or die $!;
$doc->printToFileHandle($fh);