The arrows aren't special except for the fact that they're stupidly persistent. They'll break against durable enough armor or thick enough walls.

But yeah, it's a wording problem. They aren't 'smart' arrows, but Archer can say, position a target way behind another target.

Like:

T3

T1 ---------> T2

Plus the Luck check isn't nearly as bad as the Bolg.

@A++ He has the Palladium lying around in there. A++ is equal to a Divine Mystery, and, even if it doesn't really do much, it's origin is definitely Divine.