Albedo build recommendations
Albedo is a character that can summon a Geo Construct from his Elemental Skill which deals damage on a 2 second interval whenever enemies in the field are damaged. His Elemental Burst provides 125 EM to the party, which is good on teams that rely on amplification reactions, such as Vaporize. It is worth noting that since his stat priority is focused on DEF (Elemental Skill scaling), you might want to skip casting Elemental Burst if your team doesn't benefit from the 125 EM buff. Another option is to build him with ATK-DEF Hybrid, which ends up with lower Skill damage but higher Burst damage.
Regarding Weapon Choices
Albedo's Elemental Skill scales with Defense, which is why the Base ATK from the weapon doesn't matter that much. Harbinger of Dawn offers a lot of Crit stats which is why it is one of the strongest weapons for him despite being a 3 star weapon. The downside of this weapon is that you'd need to keep Albedo's HP at 90% or higher to benefit from the passive, so it might be annoying to use against certain enemies which has a HP lowering debuff, even when off-field, such as Corrosion.
Realistically you are only able to get 2 stacks of this weapon's passive and this requires setup. Generally just use Harbinger of Dawn instead and give your Mistsplitter Reforged to another sword DPS character.
Equipping this weapon will decrease Albedo's own damage significantly but he is one of the better Freedom-Sworn holders since he can trigger the passive quite easily to buff your other party members.
Regarding Artifact Sets
Due to Albedo's skill snapshotting upon cast, you need to either wait ~12 seconds before starting a domain/fight to reach max stacks or recast his skill to benefit from the DEF and Geo DMG bonus provided by the 4 piece set effect.
This set is used for the 4 piece set effect which has good uptime on Albedo. Worth noting that this set decreases your Elemental Skill damage by a lot if compared to the other offensive sets.
If you don't have another character in your party that has this set, you can use this set on Albedo. You might want to get some Energy Recharge substats to maintain your Elemental Burst uptime for this. It is also worth noting that this set decreases your Elemental Skill damage by a lot if compared to the other offensive sets.
Regarding Artifact Substats Priority
ATK and Energy Recharge substats are only valuable on a Hybrid Albedo that casts his Elemental Burst.
Artifact stats priority
crit rate, crit dmg def% atk% er def atk