Sheng Long Gradilla said:
You need to put a lot of pressure when the handle is too thick, otherwise it will accidentally fall off from your hand.
I know how to use the katana. That weapon was developed with perfection as a goal. The handle is perfectly sized so you don't have to grip with your hand and can draw it in a single fluid motion at the same time you do a cut. The katana has never had a standard handle size, a special handle would be made for the owner, so the weapon would be perfect.
No matter if you are a true master and know all the fundamentals and everything there is to know about a weapon, if it's defective, inappropriately sized or anything, you won't be as effective with it than you would be with one properly designed.
In fact, that's the reason masterwork weapons give a +1 to attack.
As for the first, not nessecarily. If this were the case, you could not slide in between positions or switch grips. Figer manipulation is a later lesson, and it shows that such pressure is not needed.
For the second, agreed, the katana was created with perfection in mind, but it was not a perfect weapon. Should you break your sword, another would have to be used, or you used the katana at a shorter range. Broken katanas and other weapons were a common sight when in battle field combat, especially against armor.
For number 3; are you sure about that? The whole point of combat training is to be effective in any situation. Also remember that a number of weapons were originally created as tools, especially in Asian regions. They were not created for combat, but required minimal modification to improve performance.
As for claiming 3.0 rules didn't work, I did no such thing.

I made a sinle house rule to keep min/maxer's from attempting to use giant sized weapons. When common sense is applied, 3.0 rules work fine.
Let me give another anecdotal example. We had an 11 year old come into Iaido. Katanas (longsword) were too large for him to draw and use effectively. The instructors solution: give him a wakizashi (shortsword). He used it as a two handed weapon, learning katana techniques, and learnig them well. There was no change in skill level when because, as he grew older, he had to get used to a larger weapon. He applied the same principles equally.
You can argue that said 11 year old is not the size of a halfling, but the point is that he used a short weapon in the same manner as is larger equivalent. There are also other exmaples of adults using European shortswords to teach longsword techniques to young children. They didn't use specially made weapons, mainly because they could not afford to waste the steel. There is a reason why the weapons are named 'long' and 'short' swords.
Now if you accept this example as true (you may or may not), why can't other smaller creatures do the same?