You do not have to forcearray everything, just those things that actually can be repeated. In this case you might be better off using a module that'll let you tweak the created datastructure. Something like:

use strict;
use XML::Rules;
use Data::Dumper;

my $parser = XML::Rules->new(
    rules => {
        _default => 'content',
        Variable => sub {$_[1]->{Name} => $_[1]->{Value}},
        IP => 'content array',
        'VariableConfig,ServerConfig' => 'no content',
        Server => 'no content by Name',
        Config => 'pass no content',
    },
);

my $data = $parser->parse(\*DATA);
print Dumper($data);

my @FQDNs = map {$_->{FQDN}} values %{$data->{ServerConfig}};
print "@FQDNs";

__DATA__
<Config>
  <VariableConfig>
      <Variable>
        <Name>NAME</Name>
        <Value>somevalue</Value>
      </Variable>
      <Variable>
        <Name>NAME2</Name>
        <Value>somevalue blah</Value>
      </Variable>
  </VariableConfig>
  <ServerConfig>
     <Server>
        <Name>blue</Name>
        <IP>xxx.xxx.xxx.xx</IP>
        <IP>xxx.xxx.xxx.xx</IP>
        <FQDN>blue.some.domain</FQDN>
     </Server>
     <Server>
        <Name>black</Name>
        <IP>xxx.xxx.xxx.xx</IP>
        <IP>xxx.xxx.xxx.xx</IP>
        <FQDN>black.some.domain</FQDN>
     </Server>
  </ServerConfig>
</Config>
[download]