Snippet to provide minimum package weight in FedEx Rate Request. WooCommerce FedEx Shipping Plugin with Print Label - https://www.pluginhive.com/product/woocommerce-fedex-shipping-plugin-with-print-label/

functions.php

/**
 * Snippet to provide minimum package weight in FedEx Rate Request.
 * Created at : 13 Nov 2018
 * Updated at : 13 Nov 2018
 * PluginHive Plugins : https://www.pluginhive.com/plugins/
 * Gist Link : https://gist.github.com/varun-pluginhive/42b90d1a70c8f85128b417ee5ebb99bf
 */
add_filter( 'xa_fedex_rate_request', function($request){

	$packaging_types 	= array( 'FEDEX_ENVELOPE' );		// Packaging Type
	$min_weight 		= .1;								// Minimum Weight

	$packaging_type 	= $request['RequestedShipment']['PackagingType'];
	$weight 			= $request['RequestedShipment']['RequestedPackageLineItems'];
	if( ! empty($packaging_type) && in_array( $packaging_type, $packaging_types ) ) {
		foreach( $request['RequestedShipment']['RequestedPackageLineItems'] as &$line_items ) {
			if( $line_items['Weight']['Value'] < $min_weight ) {
				$line_items['Weight']['Value'] = $min_weight;
			}
		}
	}
	return $request;
} );