Wouldn't you need two identical mirrored forms? If an asymmetrical blade?

Two forms might be needed. However, the relief might be symmetrical with just the outline being asymmetrical.

As I said, I don't have a high-end blade for reference. The cheapish paddle that I have that is cupped end to end just has a dihedral with no cupping (or not much) side to side. I may end up trying to find a high-end blade that I can get the general dimensions from.