Simply put, a will of inheritance leaves valuables; an ethical will leaves values.

This non-legal document is basically a letter to loved ones; an opportunity to articulate thoughts and feelings that you may not be able to say face-to-face.  It could convey your good wishes, how much they have meant to you, ask for forgiveness, provide forgiveness, etc. 

This letter will take but a short bit of your time, but to the recepient, the gift will last a lifetime.