It seems that Socrates did not have a formalized knowledge theory. He contributed to perfecting the philosophical dialogue in the sense that you can only find some answer if you are doing the correct question. So most part of the search for an answer comes from stating what you mean with what you are saying in your question and then refining your question.
"Is love a good thing?", what do you mean with love? Is there more than one kind of love? Do you mean that love is a virtue? What is a virtue?
Through reasoning you may reach the definition of the concepts present in the question, so that you will get your answer, the correctedness of the answer depends on this work of what is the question about and what you mean when you say such words, after which you can reach a logical conclusion to the problem.
Plato, influenced by Socrates, gives great importance to dialectics as the instrument for knowledge in his development of a formalized knowledge theory. Although Socrates had a method of inquiry he lacked an ontology and as such, truth would rely solely on the logic conclusion of correct argumentation; he differs from sophists who rely on argumentation but claim that there's no truth, that it is all a matter of perspective. So even if Socrates thought that there was no way of being completely certain about finding an ultimate truth, he certainly was not relativistic like the sophists.
If you say Socrates' epistemology was diminished (and I'm not certain about why you say that) I think it is only a matter of incompleteness in his theory, but his thoughts were very important to development of Plato's theories.
