I click on the sign button and get the following "this transaction refers to one of your wallets, but that wallet is a watching-only wallet. Therefore, private keys are not available to sigh the transaction."
The error you are getting is telling you that "the offline computer I have Armory .96.4 loaded on" that you are attempting to use to sign the transaction is also only using a watch-only wallet.
As Carlton Banks has said, you need the "full" wallet that contains the appropriate private keys to be able to sign the transaction.
On the offline computer I have Armory .96.4 loaded on a jump drive and start that version.
If this "jump drive" does NOT have the full version of the wallet containing the private keys, then you will NOT be able to sign the transaction to recover the coins.