If you recently destroyed an eligible Season 1 item that could have been otherwise converted into a Tier Set piece via the Revival Catalyst, you can easily get it back!
Head to the World of Warcraft Item Restoration page and Begin Item Restoration. You can use the service once per week to restore items that you sold to vendors, disenchanted, or destroyed.
When you log in and select your server and character, the service will provide you with a list of items you recently deleted/disenchanted/vendored. You can restore the items and they will be sent via mail to you. It’s definitely worth a shot!