Okay, so. you walk up to me, you aim at me, and you say you're going to stab me in the stomach if I don't do what you want. Okay, so you're aiming, that means you're in a stance of preparation to engage me. Now aiming is neutral if you want to defend, or attack. But in this context, you are definitely on the offensive. So say you want to make sure that you start off, offensive.
Prepare offensive. You prepare to attack aggressively the moment I move. Whether I attack you or try to run. This means that even if I attack you first, you will attack aggressively. Which is what most gangers tend to do.
I see you as a threat, I want to prepare my defense. So I would prepare guarded. You attack me, I go straight into posture 'guarded.'
Now, what does this do? In the case of a predictable attack, you can prepare your reaction to it. Setting your posture. If you want to fight aggressively, even if the other person attacks first. Or if you want to ease forward and take a jab at the other guy to start the fight, but you're still smart enough to keep your off-hand up to guard your face.
This will allow you to choose to go all in and be on the offensive even if people are attacking you. Or go straight on the defensive, even if you're attacking. Both already have their own disadvantages.
This will also do nothing when you're ambushed. If you're walking down the street and someone steps out from the shadows and shoots you, you don't have time to 'prepare' so your stance negates to the defensive. As your target isn't in sight, you also don't have time to prepare specifically for the interaction and the nature of an ambush requires you to be offensive. So you start offensively.
Moments when this is useful:
Gangers specifically. "I'm going to F you up." "No, I'm going to F you up." Neither is fighting defensively, neither are going to hold back. So it makes sense for both to be offensive, and given they have forehand knowledge of the conflict, they should be able to choose how to engage.
Being mugged: If I'm getting mugged, I have the seconds required to gauge my opponent and decide if offense or defense is best for me in this situation. But attacking first negates the whole "I'm mugging" you aspect from the mugger and could force him on the defensive, which could be something you might want to avoid.
Why would the person who's going to weigh in aggressively and punch wildly till the other person is down, be fighting defensively? just because the other person doesn't hesitate to attack? You literally have the time to prepare and go "if he attacks me first, I'm going to maul him."
Could this be abused? Probably.
are there ways to stop it being abused? Make it so posture "offensive" requires you to aim. Or takes a couple of seconds to kick in.
"Jack begins to assume an offensive posture."
"Jack has assumed an offensive posture."
Spars/UMC fighting. You no longer have to decide which person is going to initiate giving a disadvantage to someone who might have wanted to turtle up originally but had to go aggressive because of the other person. It also gives a dynamic going into the fight. If Jack Turtles, Bob might want to go Kamikaze. Starting the fight with a pre-established strategy.