Bongoy, you need to understand that you are not dealing with a vendor that can afford to just take back merchandise because you decide you don't want them. As you have worn them, the seller can no longer sell them as new and must resell them at a loss. Why should the seller lose money because you have made a purchase in error? How is that fair?
If they were defective, you would have a case and I don't think anyone would be against you. However you admit that the fault lies within yourself and it is there that you must find relief. If the 'vendor' can't provide you the information you desire, because it doesn't exist, then you can't turn to Allen Edmonds for relief; the relief must come from you and the seller.
The only fair solution is that you make the seller whole, by providing a restocking fee so he doesn't lose money due to your error. If 15% is too much to handle, then suggest a fee that is fair; not one that you wish to pay, but one is that is fair.
A restocking fee is not unheard of in cases like this and many vendors with more resources than this seller use them as a way to cover losses that occurs when people return perfectly acceptable merchandise, that the business will have to resell at a loss, because it is now 'used'.
The world isn't fair, but you can be.