The ability to fight really, really well. This typically comes from years of study, and the sacrifice it takes to become the best in the world. You've got to be dedicated enough to train when you don't feel like it, to find a way to train around your injuries, to put other things aside for your training. You've got to essentially be married to your training to be "great".

Technique, knowledge, fitness, heart, Humility, empathy, co-ordination, instinct but most importantly is Intelligence and common sense.