The Taiji sword is flexible as part of its usage. Only the top 3rd is very sharp and used for swift slicing movements with the bottom third of the sword thicker and blunter and able to block. If you used the tip to block it would break. The flexibility is to that the sword can be used to cut the opponant through the armour (not the knights of old England type armour, but the leather petal style stuff if you press the sword hard enough against the opponant the sword will bend and can slide up between the gaps.) The sword should be able to stand its own weight on the tip but still be flexible to bend and then return to shape. Many of the modern cheaper weapons are made of lightweight aluminium which is much more flexible and fine for shows but not really for application.
It is also well to bear in mind that practicioners of contemporary wushu, which combined Chinese martial art technique with gymnastics, use VERY lightweight and highly flexible weapons. This is because their gymnastic routines would not allow them to handle the heavier, more traditional weapons.
The monks to which you refer actually use modern wushu-type weapons because much of what they do actually IS wushu as opposed to old, traditional forms. I have seen these "monks" in demonstration and it was several kliks below pitiful. They have no technique, their qigong demonstrations were no more than cheap tricks, and they are no more Buddhist monks than I'm a Catholic nun!
Goldendragon7 is quite correct about the spear's tassle. It is not used to distract; it was used to prevent blood from running down the shaft and making it slippery.
However, I will say that qi will NOT cause a "hard" blade to break.
A good blade, correctly made, is not brittle, nor is it overly-flexible (such as we see with wushu type blades). It has a strong blade which is very slightly flexible (in the case of the Jien; the double-edged straight sword). This flexibility has nothing to do with demonstrating qi; it has to do with making the blade strong enough to cut and thrust but flexible enough to withstand a blow from an opponent's weapon.
i thought it would be obvious that the reason why the swords are so flexible is because the contemp wushu forms are so acrobatic orientated, that the weight of a real sword would hinder the performance. the swords used in those routines are extremely flimsy and may as well be made out of cellophane paper. even a 10 year old kid could make it shake like mad. i highly doubt chi transmission has anything to do with it... personally flimsy shaky 'blades' aren't very attractive to watch, but it's too much a norm these days. there are even standardized weight for blades in wushu comps.
Ekkaia is correct. REAL Chinese swords don't flutter. Spear shafts ARE somewhat flexible, but not near-elastic like the wushu types. The Staff should be made of hardwood rather than overly-flexible waxwood which is what wushu stylists use.
Wushu uses a lot of gymnastic maneuvers, so they need to use very lightweight weapons. What they do is NOT real Chinese martial arts; it is a mixture of gymnastics and martial arts intended for spectator appeal and nothing more.
