The manuscript status shows "required reviews completed" once all the reviews have come in. After that, the paper along with the reviews could be waiting at the editor's desk for a while before he has time to look at them. This would probably account for the status having remained the same for two weeks.
For many journals, the status would change to "with reviewer" once again if the paper is sent for additional reviews. Since this has not happened, I feel that perhaps the editor is not referring to additional reviews.
There is a possibility that by "one or two more review comments" the editor is referring to a few additional comments by the same reviewers. One can't be sure, but perhaps the editor has found some of the reviewers' comments unclear, and has asked for clarifications, or the editor has a view slightly different from the reviewers and has asked for their opinion. If that is the case, you wouldn't probably have to wait too long, as it will definitely be quicker than getting additional reviews done.