User blog comment:ACWeapons/RWBY Pairings - Possible Children Ideas/@comment-25110963-20160504081815/@comment-24573226-20160605040716

Arc if blond. Rose if not.

Based on... I dunno, the theory that the kid gets the surname of the parent it takes after more. Since Yang got Long and Ruby got Rose.

Or both. i.e. Pyrrha Rose Arc.