Splendor of Tranquil Waters is the closest fit on the game's own numbers: Kamisato Ayato's kit multiplies HP, and a weapon is ranked here on whether its ascension stat and its passive act on that stat. Key of Khaj-Nisut, Wolf-Fang and Primordial Jade Cutter come next. No playtested ranking has been imported for Kamisato Ayato, so this is arithmetic over the kit data rather than a damage measurement.
Run Heart of Depth on Kamisato Ayato, with Nymph's Dream and Tenacity of the Millelith behind it. Main stats are HP% sands, Hydro DMG Bonus goblet, CRIT Rate / CRIT DMG circlet. Roll substats in the order CRIT Rate > CRIT DMG > HP% > Energy Recharge.
Talent priority is Normal Attack > Elemental Skill > Elemental Burst. The Elemental Burst costs 80 energy, which is what an Energy Recharge target has to clear.
The strongest team is Kamisato Ayato, Furina, Ororon and Xilonen, built around Kamisato Ayato: Electro · Electro-Charged.