What's wrong with this sentence?

I have been told that the sentence below is poorly written.

Also called possessive determiners, possessive adjectives refer to words which modify a noun by showing a form of possession or a sense of belonging to a particular person or thing.

Is it OK to rephrase in the following way?

Also called possessive determiners, possessive adjectives ARE WORDS which modify a noun by showing a form of possession or a sense of belonging to a particular person or thing.

What do you think?

Thank you.