sort is placing the values in $something_else::a and $something_else::b since it was called from package something_else. The workaround is to tell sort to pass the values as parameters by using the ($$) prototype:

sub fetSort($$) {  # Prototype necessary.
    my $ftA = $_[0]->{"fet"};
    my $ftB = $_[1]->{"fet"};
    $fetType->{$ftA} <=> $fetType->{$ftB}
}

package something_else;

sort netFetObj::fetSort @{ $OBJ->{"fets"} }
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This negatively affects performance, according to the docs.

In the future, please use <c>...</c> around your code rather than (an unclosed) <pre>...</pre>, as per the Monestary Guidelines. A janitor will have to fix it for you.