Too light
not at all. I was a beginner and I was a small kid. I enjoyed playing with it.
A beginner shouldn't be overly concerned with his/her racquet, they should find something
comfortable and pick it up and play with it. As they learn and their technique improves, they will learn about what they like, and what they dislike in a racquet, and will pick a new racquet accordingly.
How many good players can legitimately say that they would not be the player they are today if they weren't taught tennis for the first time with a wood racquet or a ps85 or whatever the case may be? None that I know of.
which racekt in general helps a beginner improve as much as possible and also fast with a lot of dedication and time?
To answer the op, it really doesn't matter IMHO. At a beginner's level, coordination is most important. A beginner should be practicing technique. Learning when to turn one's shoulders, or move one's feet correctly has nothing to do with the racquet they hold in their hand.