Birth charts don't provide fighting skills. We're not born with those, we learn them. A birth chart might show a predilection for aggressiveness and/or a strong desire to fight, although what kind of fighting varies from person to person. Some people are very physical, and when they fight, they fight physically. Others are verbal fighters. Some people fight by beating up whoever they come into contact with, literally or figuratively, while others fight for a cause. Fighting instinct can also play out in the form of competitiveness or seeking personal challenges, ie running a triathlon. That's also a Mars implication.
No matter what your Mars placement is, you only have the fighting skills you've learned. That in turn depends on your life experiences and your culture, not your Mars. If you grow up in a ghetto, you probably learn street fighting early on. If you grow up in a nice middle class home where you're told to use your words and not your fists from day one, you probably won't be that physically aggressive.
Anyone with Mars in the first is going to have it as part of their public persona, no matter what sign it's in. Anyone with Mars in Aries is likely to be a born fighter in some sense. Maybe they're a street fighter, or a competitive boxer, or maybe they have a strong desire to compete, period, or maybe they go out and climb Mt. Everest, or maybe they like winning arguments. Maybe they become a social cause warrior (Gloria Steinem, for example, has Mars combust in Aries, and Scorpio rising, which makes it her chart ruler, and she's certainly a warrior, though in a very peaceful sense).
Mars in Capricorn teams up with Capricorn's drive and desire to succeed. In that sign, it's most likely to manifest as desire for challenges and desire to win. Mars in Leo seems to team up with Leo's sense of pride, and would speak to a strong self defense instinct. Mars also represents passion, and in Leo and/or the fifth house, it would put its energies into creative work or other pursuits that the chart's owner deeply enjoys. Scorpio brings out the dark and edgy side of Mars, and since Mars is also sexual instinct, that part of it shines in Scorpio. Eighth house shares the dark and edgy implications, and it's also the house of taboos. Someone with Mars in the eighth might have to deal with taboos against the things Mars represents--aggression, assertiveness, passion, sexuality--as a key issue in their life.
Bottom line, any of those placements for Mars would be powerful, but each is powerful in a different way.