• You can retrieve the name attribute directly, no need to search for the first attribute.
• You need the attribute object in order to be able to remove the attribute, anyway.
• Use the getValue method to retrieve the value of the attribute.
• Minor: "reader" sounds like a XML::LibXML::Reader instance, not a normal DOM object.

#!/usr/bin/perl
use warnings;
use strict;

use XML::LibXML;

my $xml = '<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Tr
+ansform">
<xsl:element name="foo">
<xsl:value-of select="bar"/>
</xsl:element>
</xsl:stylesheet>';

my $dom = 'XML::LibXML'->load_xml(string => $xml) or die;
my $xpc = 'XML::LibXML::XPathContext'->new($dom);

for my $element ($xpc->findnodes('//xsl:element')) {
    my ($name_attr) = $xpc->findnodes('@name', $element);
    $element->removeAttribute('name');
    $element->setNodeName($name_attr->getValue);
}
print $dom;
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($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
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