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.