Highlighted weapons are free options.
Beidou combines off-field damage with defensive utility in form of interruption resistance, damage reduction and a small shield at [C1]. At [C6] she additionally reduces Electro RES of nearby targets.
In Stellar Glimmer teams at [C6] she additionally reduces Cryo RES and buffs the active character's Elemental Mastery.
Beidou's Burst hits require more than one enemy to bounce and can bounce onto the same target several times. Due to this, Beidou's damage is highest when facing 2 enemies.
Weapons are ranked based on Beidou's personal damage. Weapons that help with energy should be prioritized if you can't build sufficient Energy Recharge otherwise.