I have read on alot of sword sites that no real sword ever have a round handle because that would make the sword twist in your hands and make true cuts impossible, but it seems like the warring states and spring and autumn bronze swords have round handles. So is it true that no real swords have round handles?

Not nessessarily. Alot of sword in China does uses round handles. But these are either (1) Swords of ethnic minority and civilian or (2) the handle itself curves. So even though they are round, you still have firm grip of it.

It is true though that they are quite rare precisly for the reason you described

The round handle also makes it difficult for the user to know where the blade is without looking. By having a more elongated profile, the user can feel with his hand the orientation of the blade.

The quality training of the sword player determines the mastery of the sword.

Agreed with Lj on having a more elongated profile where te user can feel with his hand the orientation of the blade.

If the sword player is centered and relaxed enough, he can feel the tip of the sword.
It's an internal martial arts practice maneuver.

Recently played with a han jian. .
loved the feel.

Need to change my mindset and technques of not having a sword guard.

Depends on the structure of the sword & their training, one can playing w/ it as a two handed sword.
The trick is to look at it as a shorter metal spear.

You answered your own question. Swords can have 'round' (cross sectioned) handles. It is no more risky than a pole axe having a round pole if the wielder is paying attention.
I dont see how it would be a great concern. Swords of this period (East Zhou) were thrusting weapons so used the point primarily.

I've been looking around for the dimensions for a Han-era jian. I'd like to make a wooden simulator, and if possible, simulate the balance as well, for http://www.zhengwutang.com/chinese/jian/hanjian/hanjian.htm ... but the dimensions are a bit sketchy. Can anyone point me to a place where I can get some information on the demensions for a replica in that style of a sword?

Thanks.

Qaexl