How to configure an approver without Reject option?

Summary

We would like one of the approver in approval chain to provide only comments. He/she should not have authority to reject a transaction.

Content

The business requirement is to send a transaction to a "Reviewer", who should review it and give feedback. For example a termination request must go to legal advisor for his/her feedback/advice before HR manager can take any decision. The legal advisor is not authorized to approve or reject a transaction. The purpose is only to get legal opinion before a decision can be taken. We have other approvers in the chain as well who are authorized to approve or reject. So we cannot set up early completion setting option at task level because it will be applicable to all approvers. Has anyone