The Midnighter automatically analyses every situation he is in as a combat scenario, his computerised senses instantaneously checking out multiple battle strategies until he has located the best one to win the fight at minimal effort.
To aid him in the actual fight he has heightened reflexes and strength, and a superb knowledge of most forms of combat.
In addition Midnighter has superhuman durability, and is designed with a number of redundant systems (it was recently revealed that he even has a "back-up heart"😉.