The NetRep Ruling Digest made me think that I should be able of doing the trick because they were talking about an sceneario where you were able to use the same/different wizard/ringwraith as the one previously revealed. Which would be not possible if revealing this last wizard/ringwraith counted as "revealing" in the sense of "revealing your wizard/ringwraith" from the excerpt of the rules you've posted.
Let's see if there is any other plot twist in this story

EDIT: You're really fast Konrad!
Summing up... what should I do now? Should I ask my opponent, before a match, what does he think about "revealing your ringwraith", and depending on the answer just remove my ringwraiths from the deck? As a non english native speaker I don't see myself arguing in such a specific level of detail because sometimes I get lost in the middle of this "legal mambo-jambo"...