For any card like this where there's an effect that happens only if your card is revealed, or one of your opponent's cards is revealed, I see two cases:
Case 1: The card is good enough to be worth taking in hidden mode, where the effect will only happen some of the time. In this case, doesn't this mean it'll be too powerful in normal mode, where the effect happens all the time?
Case 2: The card is too weak in hidden mode, so it's only worth taking in normal mode. Then why bother having the revealed condition at all?
Any card that interacts with the hidden/revealed mechanic is going to be very hard to balance for both modes simultaneously. Oracle kind of gets away with it because the fact that its main effect is strictly better in normal mode is offset by the fact that far sight is a more powerful keyword in hidden mode.