(1) The first judgment is about the intention or will, and it is the judgment that some choice or intention is right or wrong.
(2) The second judgment is that it ought to be done or ought not to be done; this is the kind of judgment we associate with conscience. Note that it is not the same as (1); this judgment is action-oriented:
This judgment, inasmuch as it is not constituted by the mind, but announces and imposes itself as a determining principle for the will, that is, as a principle of action, is called the Moral Law, the Law of Reason or the Law of Conscience. With reference to the subject, that is, to the mind that passes it, this judgment is spoken of as a conviction of Obligation or of Duty.
Thus the idea seems to be that in addition to our sense that something is wrong, we have a sense that we are obligated not to do it, or, to put it in terms that he later uses, that something's being right is a reason to do it, and something's being wrong is a reason not to do it. (Whewell's terminology in describing this judgment is from Francis Wayland's The Elements of Moral Science, which he quotes later.)
(3) The third judgment is of the merit or demerit of the agent who performs the action.
(4) The fourth element is actually an emotional response, analogous to the emotional response we get with our sense of beauty: we regard good acts as pleasant, and with admiration or respect, and bad acts as unpleasant, and with disapproval or disgust.
This seems related to a similar idea in Dugald Stewart's The Philosophy of the Active and Moral Powers of Man, which argues that "the state of our minds, when we are spectators of any good or bad action performed by another person, or when we reflect on actions performed by ourselves" has three components:
On such occasions we are conscious of three different things:
(1.) The perception of an action as right or wrong.
(2.) An emotion of pleasure or of pain, varying in its degree according to the acuteness of our moral sensibility.
(3.) A perception of the merit or demerit of the agent.