In my opinion, it is a number of things which determines how combat is won. The two that are the most important is skill and motive. Skill is important because it will enable you to fight better, and have a better chance of survival. Motive is why you fight. If you are fighting for your homeland and its survival, or if you are in a losing situation you will have an edge. For example, the Germans facing the Russians outside Berlin. They knew they had no where to run, and so the ragtag army held them off for two days against all odds because they had motive to fight. Equipment is a factor, but it can be dismissed. The same can be said for terrain. It is a bonus, but having the right terrain does not ensure victory. Morale and skill does.
In that scenario it looks like the person you describe is a Roman facing a Greek phalanx or something similar to that. But personally I do not know enough about the other side to see who would win. What are the others thinking?