After reading through the forums, I don't see a good spot to put doctrine discussions. So...I'll put this here and move it/remove it if requested to do so.
Let me start off by saying that I'm going to talk about a problem with Iaijutsu reaching back to before the 1st Edition RPG came out. Also, I'm going to source in some of my own training in Iai, Chinese philosophy, and martial arts. I will (eventually) get around to the current iteration of Iaijutsu, but that will be a bit further down.
In the 1st Edition fiction, there is an implicit understanding of the variance between Iaido (the way of being present, a doctrine which is extended into a strategic understanding of kenjutsu by Kakita) and Iaijutsu (the specific techniques of kenjutsu aligned by Kakita into waza which he executed in response to emerging operational requirements - in this case, winning sword-fights). His answers to Lady Doji's questions (for example) demonstrate the way of being present in action in other fields. As does Lady Doji's discussions with Shinsei, but let's set that aside for now.
In the mechanics of 1st Edition, Iaijutsu is a distinct skill from Kenjustu, rather than either someone's individual style (as expressed perhaps through a combination of Advantages and Techniques) or as a set of tactical implementations of doctrine (mechanically a technique). This was done for a couple of reasons - some obvious (having a separate dueling mechanic) some less so (the need to explain why Crane cards had high Chi and low Force). Both were solvable in different ways...
Anyway. From here things get dicey, mostly because we take this design decision and embrace it for the next twenty years as an involute separation. One which, oddly enough, actually cripples multiple Clans along the way.
Iaido: The Way of Being Present
The Way of Being Present is, first and foremost, the idea that one lives in the here and now, to the absolute fullest, with every moment being the summation of a life well lived. It is embodied to some extent in the code of Bushido, and expressed clearly in the quote on Toshimoko's card "For the coward there is no life, for the hero there is no death."
Stated as such, it is clear that Iaido is the precursor to Iaijutsu (techniques of being present in a sword fight). One could learn to fight with a sword (kenjutsu) or a spear (sojutsu) and apply the idea of Iai to that skill. One could apply other ideas - the Principal of Resistance, Mobility, Spatial Control....the list isn't exactly endless, but it's deep enough.
Iaido as Doctrine
So, what then makes Iaido unique as a doctrine? I would argue for the following, though other interpretations are clearly possible and discussed endlessly..
To be present in the now - is to be empty of preconceptions, aware of the possibilities stretching forth from it, and select the desired outcome
The summary of a life - everything is brought forth, nothing held back or in reserve. The commitment to the moment is absolute, for it is only in THIS moment that one can act.
Doctrine is not directly translated into strategy, tactics, or operations but influences the space from which the practitioner develops and selects responses. In the case of L5R, one might imagine any number of new options using the L5R beta framework.
Iai and Dueling
Lady Doji defeated Shiba in the Tournament of Heavens. Kakita defeated everyone (including Matsu, shamefully due to her disrespect for her opponents) in the first Tournament of the Emerald Champion. Obviously, the doctrine of Iaido brings with it (in L5R verse) some advantage in the world of dueling.
The advantage could be strategic, tactical, or operational - that is, related to one's control of the engagement, one's preparations and prepared responses to the engagement, or one's ability to exploit how the engagement emerges.
As described, I would argue that Iaido brings both strategic and operational advantages:
The strategic ability to predict and intercept actions at their emergence (empty of preconceptions, aware of the possibilities, and select the desired outcome)
The operational ability to project sudden force in an attempt to overwhelm to opponent (nothing held back)
The second would have to be tempered by the realities of the specific techniques being employed - physics is still a thing, even in the world of Rokugan. Or is it? To what extent do we allow the spirit of a mortal man to overcome fate and physics, to perform a heroic moment and pay the price afterwards? That's a design decision, I suppose, and not suited to this conversation.
Meanwhile, the first point brings us to the question of speed. Was Kakita faster than the others? Or was he just able to predict their movement before they began and strike AS they started their movement?
Iaijutsu and Fighting: The Techniques of Being Present (in a sword fight)
What we think of as the Kakita style (Iaijutsu) is a translation of Iaido into kenjutsu, which was then bound into patterned responses (waza) which could be practiced by others. These would have to be adapted to the physical realities of the individual practitioners (their height, speed, emotional control, situational awareness, etc.). It may have become rigid over the years (as suggested in some fiction).
However, here we encounter our first chance to talk about rules. If, in 1st Edition, we had considered the Force of a card to represent it's battlefield presence and it's Chi to represent its personal combat ability, we may have come to a different understanding of Iaijutsu mechanically.
In a combat, using the doctrine as described, we might imagine an iaijutsu practitioner moving in fits and starts, pausing to assess then shifting and striking where the opponent will be, not where they are. An outside observer might not notice much difference in speed between the participants, but for his opponents the practitioner seems to be moving at blinding speed.
Iaijutsu and Dueling
Here we run into an interesting intersection of doctrine and real life. If part of the Iaido doctrine is to select the desired outcome (point 1, part 3) then, between two warriors of equal skill, the two will face each other and play out the conflict over and over again in their minds, looking for a moment of weakness. Only when one appears will one or the other move to strike a decisive blow.
Side note: You see this play out in the fiction with the duel between Kakita and Mirumoto's son. You can also see a great example of the interplay in the movie "The Swordmaster", available on Netflix.
However, the limit to this is the practitioner's practical knowledge of the specific skill in question. If I don't know how to use a sword, I will have a great deal of trouble predicting how a swordsman will move. If I don't know poetic form, then I will not be able to recognize and intercept my opponent's offerings. The limit of one's Iaido is the limit of one's breath and depth of knowledge. Similarly, an opponent of superior skill will be able to create options and opportunities the practitioner cannot understand until too late.
Finally, Mechanical Comments!
So, what does this have to do with anything? Not much, I'm just typing away at some thoughts.
OKAY, not entirely true. I would argue for two things:
1) Iaijutsu can easily be broken up (as FFG is doing now) into multiple pieces. I would argue that these should reflect Iaido, and be limited by the skill the character channels the piece through rather than specific to dueling
2) Duels are more interactive now (which is good) but lack the mental interplay one sees (and feels) at higher levels of conflict. Watch a judo grandmaster's match, or two older practitioners circling one another, watching, waiting, then finally one moves. The "techniques" they use are not that different from what any student does, but their timing and positioning is...something else entirely.
In some ways, a duel is a battle of wills in which both parties seek to open and hold on to opportunities long enough to exploit them. That idea may be worth exploring in greater detail mechanically, given the options available in the dice mechanics.