Rob Blackblade was canceled due to not fitting within the League of Legends artistic theme. No aspect of the champion was deemed worthy of keeping, so it was scrapped. Rob's place in the development cycle was filled by the champion that became Udyr.
Before the final concept of Rob Blackblade was done there was an even earlier design of him that was also included in the closed beta client's files. This version of Rob lacked an eye patch and even had a 'black blade'.