Some fights have rules. Most don't. However, a lot of people will still fight as though there are rules.
The Combat Pragmatist is a character who is defined by his or her willingness to do anything in a fight to win through anymeans.
This typically applies to "real" fights where there's actually something at stake that's more important than a cash prize, a trophy, or a title belt, and usually not professional fights in a controlled environment where safeguards are in place to prevent one side from suffering too much damage and where one can be disqualified for not abiding by the rules (though pragmatists in these types of fights are far from non-existent).
These characters are VERY Smart. They are characterized by an extensive knowledge of tactics others may consider "dirty" fighting or just by a willingness to use those tactics to achieve their goal, often against more "honorable" opponents. They are likely to think of any adherence to rules or sporting combat as Honor Before Reason.
They do not suffer from these methods, are never afraid to use a Mundane Solution (nor do they need it to be pointed out to them), never assume that the other person will fight "honorably", have no interest in a Self-Imposed Challenge, don't care if their opponent is a worthy one, and will not hesitate to attack.
They almost always have their weapon of choice either on them or near them at all times. If not they're willing to use absolutely ''anything'' as a weapon and only resort to Fists if there's no weapon nearby.
They won't hesitate to use a Dangerous and Forbidden Technique. However, there can be different levels of this. Even those who don't believe in fighting fair may still have lines they won't cross, such as refusing to kill.
These characters frequently turn out to be Wild west Heroes, Antiheroes, and Rebellious Spirits. Ninja are almost invariably these, with most exceptions belonging to the highly visible variety. Definitely not the Knight in Shining Armor, however they can be heroic.
Sometimes Weaker characters, though the truly pragmatic former will constantly seek to increase his power level and hence advantage over his enemies. It can look like Confusion Fu in practice — but it almost always isn't.
Villains can also be pragmatic, though it usually takes on a different form. Villains being normal Combat Pragmatists is usually averted, or at least not played out completely straight, as it makes them Dangerously and can possibly even lead to them being very threatning. If they are, it means they avert Stupidity and actually kill the hero instead of having dinner with him. The Villian have no compunctions to striking a woman or a child. Or hitting a guy in an unsheilded area. Or about attacking someone from behind. Or throwing sand in their eyes. Or the "Hey, You!" Haymaker. Or pretending to surrender. Or Kick Them While They Are Down.