Howcome the swords, spears, and bladed weapons in general always look so fragile in asian martial arts movies? Is it just the stunts weapons? If so howcome most western movies have weapons that look so much more solid? Or is it because traditional Chinese weapons really were that fragile looking?
Cheap props 
It was like that in Crouching Tiger, Hidden Dragon, which wasn’t a cheap movie; did they skimp on props anyway, or is there some deeper meaning? 
Huh? What kind of “deeper meaning” are you looking for?
Could it also be that studios require props that are less likely to cause any real damage due to insurance? Ask Brandon Lee, Jon-Erik Hexum, et al whether or not they would’ve prefered safer props…
There are kinds of Chinese weapons that are just as fragile looking as those shown in films like Crouching Tiger, Hidden Dragon.
Typically, a wushu steel Tai Chi sword (much like those used in CTHD) will have a blade that narrows along its length, giving three distinct zones that are used for different purposes.
The third furthest from the grip is very thin, flexible and razor sharp. This section is used for flicking and cutting at an opponent’s armour. Due to the flexiblility it can be used to “sting” like a whip, cutting through the common types of oriental armour, and then twist out, damaging the opponent. It is this part of the sword that gives the “flimsy” impression when it flexes.
The middle segment is thicker and unsharpened, used for deflecting blows, but not for direct blocking.
The third closest to the grip is thicker still and much stronger and can be used for direct blocking of blows.
Weapons such as these cannot be used for brute force cutting or bludgeoning attacks in the manner of early western swords. They reflect a maturity of metallurgy that led to the narrower, more flexible, modern western swords that are commonly modelled in fencing.
Other types of Chinese weapons are made from combat steel which is much stiffer, but a flexible wushu steel weapon is the mark of a more accomplished fighter since it is much more difficult to master.
Remember, that most weapons came from peasant tools. They didn’t have the wealth to make seperate weapons, they just took what they already had and maybe modified them a bit.
That’s the deeper meaning I was looking for – thanks.
Don’t forget that western weapons were often designed to go through heavy armor - and that style is rather rare elsewhere.
To second Armilla’s learned response (Welcome to the SDMB, BTW ), Wushu swords look very flimsy to a typical westerner, but are deadly serious weapons. These swords are highly developed, and are intended for fighters of great training. A novice with a wushu sword is a serious hazard to himself. One of my mother’s recent tennants is a wushu master, and even he needs to be careful. He was participating in a tournament in NYC a few years ago, and the tournament’s organizer insisted on uniform length blades. He’d been using a blade made to his exact needs for years, and when practicing with the longer “standard” blade that the organizer insisted on, he gave himself a 6" long by 3" deep slice along the grain of his thigh muscle. It looked like a scalpel cut (the next year, the organizer allowed personal weapons, provided they passed inspection). His personal blade is of such temper that it can flex in excess of 180°, returning instantly, and with great force, to ‘true’ when released. Nasty weapon!
Most westerners are familiar with the purpose-designed weapons for European-style warfare and social structure. Martial arts in the West are almost entirely upper-class systems (some, like la savate, are older than a large number of eastern systems), and the were only taught to nobles, social elites, and certain catagories of soldier. These groups could afford “proper” weapons, and never had to learn how to adapt fighting styles to farming implements.
Those are interesting swords, esp the one used in the tournament, since those are supposedly dull (the blades are not sharpened to prevent injury).
Anyway, I digress. There are all sorts of Chinese weapons. The most popular one is the single edged “cleaver” that’s thick on one back and sharp on the blade. There are ones that sort of like spears and there are these pole arms. The Butterfly Knifes look like a smaller version of the cleaver. They come in pairs.
Then there are the staves. Just a large piece of wooden stick. Very easily improvised.
Chinese never developed the heavily duty armour that the Western knights used. I think the thickest one is similar to scale mail. No chain mail, let alone plate.
I never asked if the tournament blade was sharpened, but his personal blade isn’t deliberately sharpened, but the tip is so thin that it really doesn’t matter: Get it moving fast enough, and it’ll still slice like a straight razor.