To sort a taxonomy in the front end by a meta_value put this in your theme:

$terms = apply_filters( 'get-terms', array('taxonomy'=> 'TAXONOMY_TO_REORDER', 'meta_key' => 'YOUR META_VALUE KEY','orderby' => 'meta_value', 'order' => 'DESC'));


To sort a taxonomy in the admin view by a meta_value put this in your functions.php:

add_action('get_terms_args', 'custom_get_terms_args', 1, 2);
function custom_get_terms_args($args, $taxonomies) {
if (in_array('TAXONOMY_TO_REORDER', $taxonomies)) {
$args['orderby'] = 'meta_value';
$args['meta_key'] = 'YOUR META_VALUE KEY';
$args['order'] = 'DESC';
}
return $args;
}