Parallelism Answer #1

1. I admire him for his intelligence, cheerful disposition, and he is honest.

Here you need to separate out the two independent clauses with a comma.

There is another variant however.

You might choose to rewrite the sentence as:

1. I admire him for his intelligence, cheerful disposition and his honesty.

Here you are replacing the second independent clause with another noun [honesty] in the series.