Scrolling through more patent designs I found this accessory registered by Namco Bandai in Europe on March 9, 2009. The unnamed controller looks like a light gun, but it is different from the Guncons currently on the market.
The analog sticks from the Guncon 3 aren’t in the spec and it has a grip that the Guncon/Guncon 2 doesn’t have. There isn’t a slot for a Wii remote either so we can rule out the possibility of a plastic remote shell.
Most likely this light gun is being made for a new arcade game. There is an off chance this could be an Xbox 360 peripheral, but Namco Bandai would need a light gun game to port over first.