All exclusives right now are strictly vanity's, no stats will be given for purchasing into the game.
Epic and Legendary gear will be the highest tiers in the game. They can only be obtained through dungeon runs and will never be sold for cash.
Cash bought gear is tier -1. It is slightly worse then tier 1, and is not customizable. Meaning there is no variety to the bonuses possible like on the dungeon gear. Example: Shadow Scimitar can drop a +5 Mite, +5 Dex, or plus +5 Vit. The store bought one might only have +2 Vit or a weak hybrid of +1 of each.
"As wars come and go, my soldier stays eternal" - Tupac Shakur