New 3rd Party, Professor Heisenberg, has come up with an add-on for the Mastermind Creations Feral Rex combiner. Here are the King's Claw. It gives Feral Rex those ferocious claws for this hands, and gives him more of beastly look and feel. These will come to match the same colors of the hands and can easily put on or off as you desire. It won't hamper storing the hands on the cannons of Bovis/Fortis.
This is slated for a September 2014 release.