(last updated: 12/28/17)
A martial artist is something above and beyond what can be considered the ceiling of human achievement. This stems from a fighter's innate command of the energy of the world around and within them, supercharging them and enabling them to perform superhuman feats that are often the subject of news articles the world over.
This section concerns itself with what can be expected of normal fighters with no clear defining characteristics and reasonable training. Most fighters can be expected to perform feats of standard martial ability--breaking a series of blocks with a single blow, etc.--trivially, and a ratio 1 fighter in this reality can routinely perform feats roughly comensurate to a bottom tier black belt in most contemporary martial arts schools in the real world.
Some fighters are capable of performing even stronger feats according to their abilities. It's not abnormal, for example, to see a martial artist perched on top of a lamppost, or riding on the hood of a car. A lot of accomplished martial artists are able to do things like beat a car down to the axles in a matter of minutes. This sort of thing is based on training; a child can take apart a car if he's tough enough, and even a 400 lb man can perform feats of great agility if that's what his martial art focuses on.
With the proper training, most fighters can't be threatened significantly by most mundane situations. They can survive for extended periods with heavy injuries in highly hostile environments, such as extreme heat, starvation or thirst scenarios. While this doesn't mean a fighter will survive handily and happily in these circumstances and that there is zero risk of death, stranding someone in the desert can end up more of an extreme inconvenience to a trained fighter as opposed to a death sentence, as survival comes naturally to those versed in the martial arts.
It is worth noting that most martial artists generally cannot be killed casually with handguns, knives, etc. Weapons generally are the keystone to several martial arts, and many contemporary martial artists are capable of dealing with them as a matter of course. This does not mean that sneaking up on a sleeping martial artist and putting a bullet in his head won't kill him! Just that you're very unlikely to be able to sneak up on a sleeping martial artist for that very reason. Indeed, while some martial artists specialize in 'iron body' techniques that can deflect bullets from bone or densely muscled areas, it's more common to simply be unable to land a lethal shot on a skilled fighter.
As a result of this, it's a common event on television news networks to hear about a fighter single-handedly taking out a group of armed bank robbers or defusing a hostage scenario with one well-thrown baseball. However, there is a difference between a casually dangerous scenario and a mortally dangerous one.
Slightly more dangerous scenarios will, however, inevitably challenge martial artists. Most military and police organizations do have precursory martial artist response programs, and while uncommon, it's not out of the question to see highly trained capture artists amongst their number. Many groups deal with martial artists by responding in large force--and there's only so many bullets someone can dodge before they find the one that puts them down for the count!
This means that for the most part, many fighters won't want to flout the law; a single unanswered threat can cut a lower tier martial artist's career short in a second, and no matter how fast you can take apart a Mazda, a team of trained soldiers driving a tank still presents a pretty clear and present threat to most martial artists below R4.
Of course, this is only true to a certain point; there are some legendary warlords and barely-human beasts, often in charge of vast criminal organizations, for whom human law simply does not apply. Firing a nuclear missile or sending an army after the likes of Vega or Igniz usually results in a fresh nuclear weapon added to Vega's stockpile, or a devastated army being forced to bow at Igniz's feet.