On Violence...
Tapas seems even more vague than most sites. Depictions of violence can include: guns, swords/fantasy weapons, absurds amount of blood (see anything Kenshin based), and varying degrees of torture.
Now in comics, there's clever ways to hide this stuff visually. But in writing, not so much. If my character is being run through with a sword, I'm going to say that. That said I have see writing where a character being cut involves, although brief, mentions of more than just blood coming out of the wound - fat and tendons for example - to illustrate how deep the injury is.
Like, where is the line? Boiled down, someone being cut through and no real description beyond that and their symptoms of the injury, that's not enough to warrant a Mature flag in my opinion. Whereas someone being cut and a description of blood flowing out of them with fat, or their innards coming out (see Saiyuki Gaiden manga. You've been warned.) definitely warrants a Mature flag. But that's two extremes.