I doubt light is going to beat water mains this dummy.
Probably the current rank 1 didnt even do his best run for water yet.
Water has 2 Echo Burst Kamihimes (Lakshmi and Ea) and Siegfried with her ele atk relic. Furthermore they can use double Fenrir. Light sadly has 0 burst streak Eidos.
Water even has access to a lot of nukes too. (Lakshmi, Shiva, Oceanus)