Saving to Drafts usually implies the message is not ready to send without further editing. When a message is finished but you wish to send it at another time, use Send Later (Ctrl+Shift+Enter) to place it in the Outbox, then FIle/Send Unsent Messages to send the contents of Outbox.

If that is the case, there should be a way to edit messages in the Outbox folder.

Thank you

You can right-click an Outbox message, 'Edit as New Message', or Move it to Drafts. But you can't Move a message directly from Drafts to Outbox; you have to first open it.

Is there anyway for a macro-task that in one click, the message is moved from the Outbox to Draft and opens for editing?

Not that I know of - probably because the purpose of the Outbox is to store messages that don't require further editing.