Beidou

Wolf's Gravestone
General best weapon, needs high investment into CRIT DMG and CRIT Rate

Serpent Spine
Outweighs Wolf's Gravestone if running an Attack buffer such as Bennett or Kujou Sara

Akuoumaru
A weapon-banner only 4-star weapon increasing in value as the team's Energy costs increase.

Redhorn Stonethresher, The Unforged, Akuoumaru, Skyward Pride, Sacrificial Greatsword, Beacon of the Reed Sea, Fang of the Mountain King, A Thousand Blazing Suns, Verdict
5-star stat sticks. They do not particularly synergize well with Beidou, but provide valuable stats.

"Ultimate Overlord's Mega Magic Sword", Akuoumaru, Katsuragikiri Nagamasa, Luxurious Sea-Lord, Talking Stick, Forest Regalia
Stat-sticks that work when their passive can be triggered. Although some event weapons are very good, they are not currently avaliable.

<sands> ATK%
<goblet> Electro DMG Bonus%
<circlet>CRIT DMG or CRIT Rate

Energy Recharge
CRIT Rate
CRIT DMG
ATK%

1) Elemental Burst: Stormbreaker
2) Elemental Skill: Tidecaller
3) Normal Attack: Oceanborne

The Energy Recharge needed will be anywhere between 100% to 180% based on what battery you are running or if you are running no battery at all. The 51.8% of Energy Recharge Sands is unnecessary when running a battery. Due to the Electro Resonance, it places her energy requirements between 120% to 140%, and if running the Emblem of Severed Fate set, the amount needed from substats is 0% to 20%.
The Electro Traveler lowers her energy requirements to 100%, and as her Energy Recharge transfer does not work with the Emblem of Severed Fate set, it is not recommended to run this set. The 2-piece Thundering Fury, 2-piece Noblesse Oblige or 2-piece Attack set will be better.