I'm With The Jerks

I'm not a gangster nor assassin,
But I do know how to fight and use weapons.
I'm not a mafia boss nor a heiress, but I lead and they follow it.
I'm not scary as a lion because I'm powerful as a devil. I'm not ice because I am cold as snow.
but my life change and that's because of that jerks.
who am I?
That's for you to find out.