Guards

[fenlander]

I have been pondering lately as to what is the logic behind a decison of a knife or sword maker on the size of a guard ie its length. It seems that the size of some guards are completely or almost completely usless (too small). A small guard in a sword may (if you are lucky) stop you getting your wrist cut off from an enemy sword. A larger guard will of course be better as it will afford more protection to the whole forearm. Why on so many of these swords that i see here, do they have such small guards ? What is the point in making a guard, say 1 inch long, why not make it larger ? The western medieval swords seem to have much larger guards, or the viking sword next to the forum title. It seems that these western swords were made far more practically than the Eastern swords, so many of which have no guard at all. Why ? Why have no guard or a very small one, is there something I am missing here ? Exception being the Chinese sai and butterfly swords. I am really curious about this. Why would a designer of a sword decide to have no guard, or one so small that is almost like having no guard, is there a good practical fighting reason ?
(I am not talking about cavalry swords)