Remove Ability for Administrators to Delete Administrators

I’ve been studying roles and capabilities and have worked with and worked up a bunch of awesome code for creating unique capabilities and roles. I have created a “Master Editor” role to maintain users with almost every capability…
However, edit_users & delete_users obviously allows for an editor to CUD users, including the existing administrators…

At the moment I’m to new at coding to be confident editing users.php but I have to be close to the solution:

if ( ! current_user_can( 'delete_users' ) ) 
// or is trying to delete an admin's $userids 
wp_die(__('You can’t delete users.')); // or administrators

$update="del";
$delete_count = 0;

foreach ( $userids as $id ) {
    if ( ! current_user_can( 'delete_user', $id ) )
        wp_die(__( 'You can’t delete that user.' ) );

    if ( $id == $current_user->ID ) {
        $update="err_admin_del";
        continue;
    }
    switch ( $_REQUEST['delete_option'] ) {
    case 'delete':
        wp_delete_user( $id );
        break;
    case 'reassign':
        wp_delete_user( $id, $_REQUEST['reassign_user'] );
        break;
    }
    ++$delete_count;
}

I can’t figure out how to check that the $userids in question are an administrators user ID. Because if I can I could add that to the die… Am I on the right track?
Thanks in advance.

Your question seems to boil down to this

I can’t figure out how to check that the $userids in question are an
administrators user ID.

Try

user_can($id,'administrator')

http://codex.wordpress.org/Function_Reference/user_can

The Codex has a warning about using role names with the current_user_can function and it is very similar to user_can so I suppose caution is order until the conflicting instructions are sorted.

Do not pass a role name to current_user_can(), as this is not
guaranteed to work correctly.

The same page also says:

$capability
(string) (required) capability or role name
Default: None

As does the source:

• @param string $capability Capability or role name.

Are you hacking core file? The users.php isn’t this users.php is it? That is a high maintenance path your are going down if it is.