Order Discounting

We are transitioning to WooCommerce from another platform. Our current platform allows us to add a simple discount line ($ or %) to any existing order after the order has been entered. This is something we use a lot.

WooCommerce does not seem to have this functionality. Instead, if you want to add a discount to an existing order, you need to add a coupon code. The problem with coupons (besides the incorrect terminology) is that you have to define the coupon and the amount before you can use it. This is a somewhat clumsy process for adding or editing a simple discount for an order.

Am I missing something? Is there a simple way to add a discount to an existing order in the admin?