I am having the hardest time figuring out the Dueling rules as to how Guards work
Does it just increase the TN or is there more to it? I would think more as they are there I am guessing for a reason. In my head there is a Left guard and Right guard.
If you attack with an asset (blade) in one hand, the right, and you are attacking the left that has no knife asset but does have shield does the TN go up? Or do you get into the guard zone then you can attack the target zone?
I am just lost. Why have them at all? For a Narrative system this doesn’t narrate well at all.
Guard zones are not entirely static as both fighters are always on the move.
So shifting an asset into the left guard is making a feint or a play against whatever they are presenting as the left side of the target.
That side might have a defensive asset like a shield or a blade. But in all likelihood the reason an opponent is attacking in that direction is because it doesn’t 
No fighter can cover all directions at once, so each fighter is trying to drive their assets past defenses to the main target zone.
If there is nothing in that zone to defend the target, then thats all to the good for their opponent, and the reason they have picked that approach in their attack.
Hope that makes things a little clearer.
Check out the website as we have some videos on fights that might help. There is also a blog that might help understand the flow of a fight here:
“Majesty, is there a Harkonnen among you?” (modiphius.net)