heavy racket usually come with small head size and claasified as tour racket. if strung with higher tension, you need a full form to swing and you can't be lazy. it help to train your form (left hand hold racket, shoulder turn....)
some info told it have less chance to have tennis elbow (probably because you need to swing in full form)
I think you also need to consider how heavy and the racquet design that you can handle. For example, in year 2007, Tecnifibre has release T.Flight 295 (http://www.xxxit's only 295g, 95 sq. in , but it's square shape flame (quite like n-code six-one 90 in 95 sq. in and light wight), it is harder that others same weight racquet give you a very solid feel.
Heavy racquet always requires early racquet peparation, which in turn requires good shot anticipation. So a heavy racquet may not be suitable for beginners.
A heavy racquet may minimize the chance of tennis elbow, but may also lead to tennis elbow because of poor hitting timing. 套用成語：水能載舟，亦能覆舟。
i did start a 9oz prince last yr when i started my tennis course (first one). my friend and i can't use it as it is too bouncy. we are lucky to get a 2nd hand wilson ps95 (~12oz). it's a bit discouraging - mishit / early prep, but it did help me to learn the form for forehand / backhand.
I'd also read an article from Tennis Magazine (Taiwan version) many many years ago about racket weight. It emphasizes that it is the racket weight to deal with vibration during impact, whether technology or peripherals .... can't help too much.
Thus, it concludes as a relative scenario. If you & your peers are at the similar power level, it's no big deal to play with a light racket. However, if your opponent is a strong & flat hitter, injury potential will be raised, especially your racket is below 9 oz.
agree that heavy sticks are only useful trading rally with really good guys.
But can't completely agree that heft is the only factor and that only heavy sticks are good for arm. The stick that has hurted me most seriously was the 375g old Dunlop MaC (woodie) when i was caught late due to its heft. My wrist broke for 2 yrs.
IMO, 2 factors are very important.
1, Swing wt. which is more relevant countering the ball's impact.
2, one's skill in playing with each racket. i guess every racket, with its balance and wt distribution, requires some different form and swing speed. If one has the right swing speed for a particular racket, it won't hurt.
Hence, i guess lot of ppl get hurt by heavy rackets that may be too heavy for them, like i was.