It certainly does display the general outline of the classical idea of an angel. It has the general form of a person in a robe with wings on the back.
The form even appears to have the hands folded in prayer.
Was incense being burned in the church? As any smoker (or ex smoker) can tell you, when the light hits smoke, it can cause some interesting shapes
like this. Just a thought, but depending on the purpose for this service, it could be just as simple as that.