The key is to start from the ITEM node, not the identifyer:
$ xmlstarlet sel -t -c "/DATA/TABLES/ITEM[identifyer/@V=1234]" test.xml
<ITEM>
<identifyer V="1234"/>
<property1 V="abcde"/>
<Property2 V="qwerty"/>
</ITEM>
Then you can pick out the bits you want:
$ xmlstarlet sel -t -c "/DATA/TABLES/ITEM[identifyer/@V=1234]/*" test.xml
<identifyer V="1234"/><property1 V="abcde"/><Property2 V="qwerty"/>
$ xmlstarlet sel -t -v "/DATA/TABLES/ITEM[identifyer/@V=1234]/Property2/@V" test.xml
qwerty