Was insurance put on the package? When you purchase insurance it automatically requires a signature if it is over $200.
Here are the policies from the post office:
An item insured for $200.00 or less receives a delivery scan. An item insured for more than $200.00 receives a delivery scan and the recipient's signature. Delivery of insured mail is subject to
508.1.0, Recipient Options, and
508.2.0, Conditions of Delivery.
So if you insured the purse for $400 then it would automatically come with signature requirement and in the event of a problem you can pay a small fee to have them track it for you. Delivery confirmation ( most of the time ) only shows when the package was shipped and when it was delivered. There's no signature and a buyer could say, "well if they left it I never got it," and you have no proof of who actually received the package as you do with a signature.
I'm not sure how much a signature requirement alone helps you. A good question for paypal.
In my opinion you were NOT in the wrong for requesting a signature confirmation but your money may have been better spent on the insurance because you get protection both ways.
My suggestion at this point is damage control. If signature requirement presents a problem for her as a buyer then it would be good for her to let people know before they ship her items.
Your customer service has to kick in here. I encourage you to be just as nice to her as you can be and let her know that you're sorry that this has caused a problem for her and you would have been glad to let it go if you had known. I'd let her know that if they return the purse to you then you'll be glad to pay for the shipping back to her with only delivery confirmation. The only way I'd do this, however, is if she did indeed have very good feedback and wasn't trying to "switch" addresses on you. If you're sending to a confirmed address then you have your protection but Paypal has always informed me that if you send to an unconfirmed address you have ZERO protection.
So I don't think you were in the "wrong" but it's better to resolve the problem kindly, get her the item, and then move on while protecting your feedback as best you can. Nothing good comes from the tit for tat that many buyers and sellers sometimes get into. I wouldn't blame her or be accusatory. I'd just say, "I'm going to fix this in whatever way is the fastest and easiest for you and I'm sorry for any inconvenience this has caused."
Unfortunately, the ebay feedback system is skewed and a good name is to be desired more than many riches so protect your name. It will bless you down the road with other buyers that are going to be a bit more responsible.
Again, I'd double check those addresses. If it's not confirmed and you don't have some proof of delivery then you have no protection. You'll be wise to verify these things with paypal BEFORE you ship and not after.