Some experts believe that John Wick may have used a Ka-Bar MBK knife during the film. This knife is known for its durability and sharpness, which would certainly come in handy for someone like John Wick. Additionally, the MBK is a relatively small and compact knife, making it easy to conceal and carry around. Of course, we can't say for sure what knife John Wick used in the movie. It's possible that he used a different type of knife altogether. However, the Ka-Bar MBK is definitely one possibility worth considering.