I kind of want to end this post right here. It would be poetic, but incomplete. It's good to read into stuff, to stretch your brain. If this wasn't a subject that stirred so much fantasy I'd feel more comfortable with that.
The fight. If you have trained well in martial arts now, in this circle, it can come into play. With a couple of caveats. Okay, a lot of caveats.
First of all, you have to survive the Fourth and Fifth Circles. If you got gutted and never even saw it coming, all the fighting skill in the world comes into the equation too late. If you stand there frozen telling yourself in your head what you should be doing as the fists and feet come in your skill won't play. To increase your chances at the Fourth Circle you have to have the second down cold. It all connects.
More addendums and caveats- you won't be at your peak, probably. Assuming you have the lithe carriage of a martial athlete on a good day, almost no one will be stupid enough to hit you on a good day. That means you will likely be exhausted or injured or sick (or drunk) when you most need your skills. At minimum, if you do the sensible thing and warm up and stretch before practice... well, you probably won't be warmed up and stretched. And, of course, when and if you recover from the freeze you will have all those annoying physical, mental and sensory deficits that come with a huge surge of adrenaline and other stress hormones. So you won't be fighting with the same body that you have trained.
Especially if you missed on Stage Two, the attack may not be like the fights you have trained for. That's just on the physical skill versus skill level. If you've trained exclusively against long range linear punches and kicks the pitcher of beer upside your head or the liverpool kiss may come from nowhere.
The Sixth Circle is also where a lack at Stage One will destroy you. If you've been trained (and are lucky enough) to disarm the threat and use his own knife on him, you may pass self-defense and step into manslaughter. If you have been coached again and again to deliver a "finishing blow" after you put your opponent on the ground, you have been training to commit assault (possibly felony assault depending on how you "finish"). Or the inverse- if you have practiced throwing a single perfect technique and waiting for the ref to call it- you will have a tendency to do it here.
There are rules in a fight. Not only have you internalized some form of moral code since you were a baby, you have seen an etiquette and flow to conflict your entire life and you have internalized a script of how violence works with your martial arts. So has the bad guy. Even sociopaths have subconscious rules, scripts. Habits. It won't be a matter of "there are no rules in a street fight" or even that you are hampered by the rules of civilization and the threat isn't. It is an interplay of your (usually subconscious) rules and the threat's. Your expectations and the attacker's script. Sometimes of your trained blind spots and the threat's actions.
The environment can be a huge difference. It's unlikely to happen on a mat or in a ring with a good floor and no obstructions and limited yet clear space. That's not a bad thing, if you've trained for it. The world is made up of weapons and opportunities. The difference between a hazard and a tool often lies in who uses it first.
Other than these little items, and probably a dozen more I am too tired pull up to my conscious brain right now, the fight is pretty much what you have trained for. Hopefully.