Damn this is an awkward question. I think you can only find out who is actually hard in a fight if they actually fight. Now just winning a fight does not make you hard IMO. If for example a smallish 10 stone person fought a 6'6" 18 stone boxer, I would say that most of the time the big man would win (unless small guy is extremely compitent at fighting). But if small guy fought well against the big man, did not give up and managed to put up a decent fight before losing I would say that he is quite hard.
You obviously can be a hard man/woman if you walk away but this act does not make you hard, it makes you smart. The people that I worry about are not necissarily hard but fight as if there is nothing to lose (i.e nutcases). These people will do anything to win and are relentless.
Now even worse than the nutcase is a hard nutcase. These people display all of the above characteristics and will probably cause somebody a great deal of harm.
As a young person I scrapped quite a bit but only if there was no alternative, i.e if I am being hit or if I was defending someone else (I am a very placid person by nature, make sure you read that tight ). But as soon as I turned 18 I began to think about the consequences and now that I am a dad I would do anything to avoid confrontation as there is so much to lose. Fortunately I rarely go out anymore so the chances of me getting into trouble are minimal now.
Right my head hurts now as I that took me ages