If it is right or not is not my thing to judje, yet japaneese arts seem to concentrate more on general rules like gripping the right way, holding in the right angle etc., than does the art of the medieval ages in europe.
That's because a proper grip will help you leverage the sword better while allowing you to keep from binding when moving through cuts and kamae. And proper angle of the blade will prevent you from bending the blade when striking (even the best blade, if struck on the edge at the wrong angle, can bend). It's all physics that apply to WMA just the same as EMA.
I'm almost certain that Iaido, the way the people of today know it, was never used in a 6 hour battle with rain, mud , distress, shock, terror and pain.
No, it wouldn't. But that's because Iaido is "the way of drawing the sword" (literally translated). The whole idea was that if you could draw your sword quickly enough, there would be no swordfight. Kenjutsu, however, was more of a classical swordfighting art, and it was used in a great many battles in the mud, rain, snow, and any kind of muck for hours on end. Plenty of samurai killed, and were killed, by it.
the least thing you'd be concerned about is, if your grip has 2 or 3 fingers on the pommel or not.
That's because you would've trained in your sword art so much, that proper grip would've been ingrained into you, and you would benefit from a proper, strong, flexible grip - and the physics it would impart to your strikes.
(start rant here...) You know, I hear all too often, people say "this is a WESTERN martial art, not an EASTERN one!"... Let's face it - there are only a certain number of ways a sword can be used. It's an extremely simple device in design and function, regardless of the elegance of its manufacture or artforms associated with it. The sword is a wedge attached to a lever, and let's face it - when it comes to the basic ways of gripping it and swinging it, it's all pretty much the same. If you look at a Kenjutsu manual alongside a Western longsword manual, you'll see a great number of similarities. The footwork is basically the same, the strikes are all the same (you can only swing a sword in so many directions), and even alot of the stances/kamae are similar. The tail guard, the hanging guard, guard of the window, and high/low/middle guard of course all exist in eastern sword forms (kenjutsu being my example here), though under different names. You still have one hand steering the sword, and one hand providing the power.
it's all basically the same! So to all those people saying that the WMA approach to swords is drastically different from the EMA approach, I have to respectfully disagree. It's just not that kind of complex.
Okay, rant off.