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