Maybe what you want is to dispatch to a sub-handler based on context? Something like:

use strict;
use warnings;
use XML::Twig;

my $xml = <<'XML';
    <XMI xmlns:UML="omg.org/UML1.3" xmi.version="1.1" timestamp="2007-
+06-26...">
      <XMI.content>
   
            <UML:Class name="Address" xmi.id="EAID_009DB5F9_3A9D_44d0_
+88BD_...">
              <UML:ModelElement.taggedValue>
                <UML:TaggedValue tag="isSpecification" value="false" /
+>
                <UML:TaggedValue tag="ea_stype" value="Class" />
              </UML:ModelElement.taggedValue>
              <UML:Classifier.feature>
                <UML:Attribute name="city" changeable="none" >
                  <UML:ModelElement.taggedValue>
                    <UML:TaggedValue tag="description" value="City" />
                    <UML:TaggedValue tag="ea_guid" xmi.id="EAID_661614
+4D_..." />
                  </UML:ModelElement.taggedValue>
                </UML:Attribute>
              </UML:Classifier.feature>
            </UML:Class>
   
        <UML:TaggedValue
            tag="created"
            xmi.id="EAID_17DA671B_9257_42f1_8AA8_0EF5F305DBD0"
            modelElement="EAID_31EB028E_30B2_430a_9168_1010A2A7B851" /
+>
        <UML:TaggedValue
            tag="ea_stype"
            xmi.id="EAID_FAF2F308_9EB4_4f83_90F6_BE8ABC10087C"
            modelElement="EAID_31EB028E_30B2_430a_9168_1010A2A7B851" /
+>
   
      </XMI.content>
    </XMI>
XML

my $twig =
    XML::Twig->new(
        start_tag_handlers => {
                'UML:Class' => \&uml_class_start,
                'UML:Package' => \&uml_package_start,
        },
        twig_handlers => {
                # purge at the end of each class section
                'UML:Class' => sub { $_[0]->purge },
                'UML:Attribute' => \&uml_attribute,
                'UML:Generalization' => \&uml_generalization,
                'UML:TaggedValue' => \&uml_taggedvalue,
        },
    );

$twig->parse ($xml);


sub uml_class_start {
    my ($twig, $elt) = @_;
    
    my $xmi_id = $elt->att( 'xmi.id' );
    my $name = $elt->att( 'name' );
}


sub uml_package_start {
}


sub uml_taggedvalue {
    my ($twig, $elt) = @_;
    
    if ($elt->parent (qr/UML:Attribute/)){
        uml_taggedvalue_attr (@_);
    } elsif ($elt->parent (qr/^UML:Class$/)) {
        print "Ignoring class taggedvalue\n";
    } else {
        uml_taggedvalue_def (@_);
    }
}


sub uml_generalization {
}


sub uml_attribute {
}


sub uml_taggedvalue_attr {
    print "uml_taggedvalue_attr\n";
}


sub uml_taggedvalue_def {
    print "uml_taggedvalue_def\n";
}
[download]

Prints:

Ignoring class taggedvalue
Ignoring class taggedvalue
uml_taggedvalue_attr
uml_taggedvalue_attr
uml_taggedvalue_def
uml_taggedvalue_def
[download]