[Tar Elenion]

Western swords are not heavy or clumsy or slow, and they are fully as efficient as a katana. Most western swords if intended for combat seldom weighed more than 3lbs (even the large two handed swords popularized by the landsknechts in the 1500's seldom weighed more than about 6 lbs, if intended for combat). These weights are comparable to that of a katana.
Rapiers, on average, tended to weigh a little more than swords.
It is highly improbable that a western sword would break a katana in combat, no more so than it would break another western sword (and just as improbale that a katana would cut through a western sword).
The thrust with the rapier is no more an assurance of fatality than the 'hack' with the sword will only result in a 'flesh wound', for example George Silver writes in his treatise, The Paradoxes of Defence (this is from about 1595):

And again, the thrust being made through the hand, arm, or leg, or in many places of the body and face, are not deadly, neither are they maims, or loss of limbs or life, neither is he much hindered for the time in his fight, as long as the blood is hot. For example:
I have known a gentleman hurt in rapier fight, in nine or ten places through the body, arms, and legs, and yet has continued in his fight, & afterward has slain the other, and come home and has been cured of all his wounds without maim, & is yet living. But the blow being strongly made, takes sometimes clean away the hand from the arm, has many times been seen. Again, a ful blow upon the head or face with a short sharp sword, is most commonly death. A full blow upon the neck, shoulder, arm, or leg, endangers life, cuts off the veins, muscles, and sinews, perishes the bones. These wounds made by the blow, in respect of perfect healing, are the loss of limbs, or maims incurable forever.
And yet more for the blow. A full blow upon the head, face, arm, leg, or legs, is death, or the party so wounded in the mercy of him that shall so wound him. For what man shall be able long in fight to stand up, either to revenge, or defend himself, having the veins, muscles, sinews of his hand, arm, or leg clean cut asunder? Or being dismembered by such wound upon the face or head, but shall be enforced thereby, and through the loss of blood, the other a little dallying with him, to yield himself, or leave his life in his mercy?

Of course most swords and longswords could be used to thrust as well. Indeed George Silver notes that 'there is no true fight without both the blow and the thrust'.

Western armour is, comparitively, little if any heavier than Japanese armour, nor is agility so greatly restricted, knights could run, fall and rise, vault onto horseback and fight with relative ease in while armoured (needing winches to mount a horse not being able to get up if knocked over are myths). Modern soldiers often carry as much weight in the field and it is less well distributed.

As far as techniques go, the historical western schools of fence were fully as developed as anything in the east from a comparable time period. Longswords could, for example, be wielded in one hand or two, thrust, cut, or used at the halfsword (where the blade is grasped with one hand, the other on the hilt, in fact some techniques are shown where the sword blade is grasped with both hands and the opponent struck with the pommel or gaurd).
Even historical western unnarmed combat was no less developed than the east and was integrated into armed combat.
To go back to George Silver, he writes of:

the old ancient teaching, that is, first their quarters, then their wards, blows, thrusts, and breaking of thrusts, then their closes and grips, striking with the hilts, daggers, bucklers, wrestlings, striking with the foot or knee in the cods, and all these are safely defended in learning perfectly of the grips.

In the end it would come down to who the better individual fighter is.

[ April 20, 2003: Message edited by: Tar Elenion ]