Do you think the weight of the racket is a big issue? She's 5'6" with a slight build.
I don't think I can improve on J011y's advice from his "The J011yroger Guide to Racquet Selection":
"The single most important thing about a racquet is that you like it. You absolutely must like the way the racquet feels to you, the way it plays, the way it looks. If a racquet feels too stiff, too rattly, too dead, too light, too heavy, the grip doesn't feel right, you hate the color, or it hurts in any way when you are hitting, then it isn't the right racquet for you. This is so immensely important. If you don't like the racquet, or if you have to think at all about it, then you will not be able to play to your fullest. You should just be able to pick up your racquet and play with it."
"With reguard to racquet weight, and racquet Swingweight. I advocate playing the heaviest racquet that you can play well with. This weight is different for different people. Some people may find anything over 10.2oz to be too heavy, some people will play with a 14oz racquet. What does this mean. The primary factor that you should be able to judge ideal racquet weight/swingweight by is being able to get around on the ball. Out of all the people you play with, or intend to play, or want to be able to play with in the near future, you must be able to get around on the vast majority of their balls. What I mean by get around, is hitting the ball with your full normal swing, and not feeling rushed, and hitting the ball ON TIME. Anyone can smoke feedballs with any racquet, anyone can convince themself that they are playing great when they try out their new racquet against Aunt Thelma, and her moonballs. When you are in competition, when you are on the run, when you are playing in the wind, when you are playing on a lousy surface, when your opponent is hitting behind you, can you get the racquet around on the ball, and hit it on time? Or are you constantly late? Anyone can hit a good shot when they have plenty of time to set up, and line the shot up. If in match play, when you are on the run if you are late on the ball too often, your racquet is probably too heavy/too high swingweight. If your ball is deep in a casual rally, but it shortens up when you are under pressure, on the run, your racquet is probably too heavy/too high swingweight.
The second factor, which should only be a factor if the racquet is WAY TOO HEAVY is fatigue. If you feel tired after swinging the racquet during a hitting session, or after serving three sets, then it is WAY too heavy. Once again it is ok to buy something with a little extra heft if you like it, and have the intention of building up some endurance, but be realistic. Are you really going to put in the effort? A 12oz racquet doesn't build up your forearm muscles while it is sitting in your bag, you need to go out and hit balls with it. . . lots of them. Don't buy the racquet with the intention of growing into it if you are not prepared to put forth the effort.
When discussing weight you will hear the argument that a racquet can't be too heavy for you because women and children played with wooden racquets that weighed way more back in the day, and Sampras learned to play with wood, and he turned out OK, so you just must be a sissy if you can't play with a racquet waying Xoz. This argument is complete and utter HOGWASH (Yea I would have said something else in an unmoderated forum.) They played with heavy wood back when that is what there was. Ballspeed was NOWHERE NEAR in the league that it is now. The ball traveled slower, so you had that much more time to get around on the ball, and didn't have to put nearly as much work on the ball to maintain depth when you were countering a slower less spinny ball. I personally hit a very very heavy ball, and have had many a club player come and tell me "When we hit, I just can't get the ball past the service line". If you can't get around on the majority of balls from the people you play with, you need less weight."
-http://tt.tennis-warehouse.com/showthread.php?t=160692
If you are looking for a new racquet, I would highly advise reading all of his epic post.
