Reliquary of Truth is the closest fit on the game's own numbers: Nahida's kit multiplies Elemental Mastery, and a weapon is ranked here on whether its ascension stat and its passive act on that stat. A Thousand Floating Dreams, Dawning Frost and Nightweaver's Looking Glass come next. No playtested ranking has been imported for Nahida, so this is arithmetic over the kit data rather than a damage measurement.
Run Deepwood Memories on Nahida, with Celestial Gift and Emblem of Severed Fate behind it. Main stats are Elemental Mastery sands, Dendro DMG Bonus goblet, CRIT Rate / CRIT DMG circlet. Roll substats in the order CRIT Rate > CRIT DMG > Elemental Mastery > Energy Recharge.
Talent priority is Elemental Burst > Elemental Skill > Normal Attack. The Elemental Burst costs 50 energy, which is what an Energy Recharge target has to clear.
The strongest team is Nahida, Raiden Shogun, Kuki Shinobu and Thoma, built around Nahida: Dendro · Overload.