Amazon has put up a listing for the Minecraft Diamond Sword Joy-Con Comfort Grip, revealing several details. If you are interested, the controller accessory, which has been officially licensed by Nintendo, is available for preorder with this link from the shopping website. You can also check out what the grip looks like with the image located just below this paragraph (more photos can be found in the aforementioned retail listing).
Furthermore, you can find Amazon’s product description of the latest BD&A accessory for the Nintendo Switch below:
The officially licensed Minecraft Diamond Sword Joy-Con Comfort Grip should last well over 1562 uses (unlike the diamond sword one might acquire in the game). The Joy-Con Comfort Grip brings the left and right Joy-Cons together to make one comfortable controller for the Nintendo Switch, so you can play as long as you like. The ergonomic rubber grips keep your palms happy and fingers from cramping. Simply slide each Joy-Con down the rails until they click, and view the player indicator lights through the front. ProTip: The Comfort Grip stands up on its own, so you can show it off next to your Nintendo Switch Dock.
The Minecraft Diamond Sword Joy-Con Comfort Grip has a release date set for February 16, 2018.