Use Of Notifiers - How To

[SteveKim]

Try using this:

 $_SESSION['cart']->weight

$_SESSION['cart']->weight returns what's same as $total_weight.
Below (within the notifier class' function update), derived from class shipping did the job calculating proper [actual] shipping weight.

   function update(&$callingClass, $eventID) { 
       if (!$this->xml_config_switch()) return;
       global $order, $insert_id;
    //Begin Shipping Weight Calculation
    $shipping_weight = $order->total_weight;
    $za_tare_array = split("[:,]" , SHIPPING_BOX_WEIGHT);
       $zc_tare_percent= $za_tare_array[0];
       $zc_tare_weight= $za_tare_array[1];
       $za_large_array = split("[:,]" , SHIPPING_BOX_PADDING);
       $zc_large_percent= $za_large_array[0];
       $zc_large_weight= $za_large_array[1];
    switch (true) {
        // large box add padding
        case(SHIPPING_MAX_WEIGHT <= $shipping_weight):
        $shipping_weight = $shipping_weight + ($shipping_weight*($zc_large_percent/100)) + $zc_large_weight;
        break;
        default:
        // add tare weight < large
        $shipping_weight = $shipping_weight + ($shipping_weight*($zc_tare_percent/100)) + $zc_tare_weight;
        break;
      } //End Shipping Weight Calculation