1. There is no conception apart from real perception. (Premise)
2. There is the conception of angelic-like entities. (Premise)
3. Therefore, there is a real perception of angelic-like entities. (From 1 and 2)
In support of (1), the only reason we are able to imagine fictional entities, such as unicorns, is because of real perceptions of horses and various animals with horns. Yet, premise (2) contends that we have the conception of angelic-like entities. What possible combination of entities could account for any fictional angelic-like entity? In fact, many claim that they have been visited by angels. Are they crazy, or is there an authentic perception? I'll let readers decide for themselves.
In any case, the argument is logically valid. The skeptic's best case against the argument is probably to undermine premise (2).