Brave Lucina

Brave Lucina is a multi-role unit. A Physical damage Support, Pseudo-Healer, and an excellent duelist due to high defense and weapon. Her IVs can vary her roles; offense banes with defense boons make her more into a support/tank role while defense banes with offense boons can make her into a glass cannon like her sword counterpart.

This specific build accentuates her multi-role capabilities.
-For A skills Fury can help her attain a greater dueling capability, the downside losing 6 HP regardless of damage prevented. Her base skill, Sturdy Blow, can also be used for budget. Other skills include Life and Death for more glass cannon capabilities or Swift Sparrow for a more safer route to Fury's HP bleed and Life and Death's 5 Def/Res loss. Another skill is Gamepedia's newest favorite skill, Steady Breath, for much greater trading against melee units.
-For B skills Renewal is taken here to help her healer capabilities for Reciprocal Aid and for Fury's HP upkeep. It also makes her deceptively tanky if utilized correctly. Other skills include Desperation if utilizing a glass cannon build, Vantage/Lancebreaker/Quick Riposte for a more generalized Duelist build.
-For C skills we just take her base skill, Drive Spd, as it really cements Brave Lucina as a support unit. Though if you really want to create a better duelist, then Threaten Def/Atk can be taken.
-Brave Lucina's Assists can vary greatly. The more generalized Reposition, the healer-centric Reciprocal Aid, or a buffing Rally skill. Here we take Reciprocal Aid to accentuate her healer capabilties.
-Her Specials can vary as well. You can use her base skill Aether but has a incredibly high cooldown. Bonfire and Ignis can be used due to her high Def stat and Luna to kill more durable units.
-Her choice of Seals can vary, but we take an HP+ seal for added benefit of healing unit with much greater HP than her own.

Brave Lucina is a swiss army knife, capable of doing multiple roles depending on what the summoner can make of her. Her great weakness is her abyssmal Res stat which makes her easy picking for Green Mages which are usually in abundance in arenas.

/////Brave Lucina +Atk -Res*/////
#Lvl 40 +10 (+4 to all stats)
#S rank Summoner Support (+5 HP, +2 to all other stats)
#+1 Atk Sacred Seal
#Optional +2 to Atk/Spd/Def/Res from S rank Ally Support for a total of: 50/56/44/38/30

#This build makes Lucina a front line Tank reaching as much as 50 defense upon being attacked adjacent to her S Ranked ally.

Ardent Sacrifice also makes her a side-healer which can be helpful to heal some damage from your main attacker while staying near so her buffs can work on him.

All damage she receives from battle is healed back as soon as she procs Aether. A -2 cooldown thanks to Steady Breath and Wrath and her high speed, that lets her double enemies often, allows her to use it almost every turn for high amounts of damage and healing. Wrath increases its damage by another 10 which also improves her survability.

#Pairings:
-Any physical unit that receives the buffs of her weapon.
-A red unit with high res that can counter her main threat: Green mages. Caeda works great with BLucina: she receives her buffs and kills her threats with no effort.
-Any supportive unit with Infantry Pulse so BLucina can use her Aether more often.

#Options:
-Rally Atk/Spd. Unobatainable right now. Only inheritable from Bridal Cordelia. This negates her healing part while upgrading her support role by a lot.

-Renewal 3. If you desire to use BLucina solely as a Healer/Support focused unit. This will allow her to keep her health up at all times. I don't recomend S rank Summoner support if this change is made.

-Any lower cooldown special (Luna, Moonbow, Bonfire) + Wings of Mercy. This is for a riskier build but way more focused on using her as an attacker. Also allows her to support dying allies either by healing them, finishing their threat or supporting their attack. +Atk boon if this build is considered.

*Any boon/bane works with this build.

///// Thanks for reading /////

If you truly want to exploit everything Lucina can do then you're fast blue lancer can get the job done. First off, Speed or attack boons can work well with this build. If you do get a diffrent boon or bane you can still compromise different ways of playing Lucina. However, if you chose her as your free summon this build can work as well if you can't roll one. Her banes should be res or hp. She has a lot of hp to sacrifice and getting a bane in res is perfect since you aren't really suppose to fight mages with her.

Distant counter allows her to ward off and scare mage units. She can definitely take atleast one hit from a mage and Quick Riposte helps her even more. You can use Vantage 3 if you don't have Riposte lying about. If threaten speed is in play and Lucina survives an onslot she can dual hit anyone in the cast of heroes. However, speedy ranged units can abuse Lucina, so if you don't have distant counter a proper way to deal with range units is to lure them in.

Lucina's weapon, Geirskogul, Grants her +3 def and is a great built in spur weapon for your allies. Most people build her as a rally support unit, but I like Lucina to be an offensive unit. Moonbow is a staple when it comes to damage. It's fast and super efficient. Swap can be, well, swaped out for another support skill. I wouldn't recommend Ardent Sacrifice or Reciprocal Aid, however. This build focuses on damage output and if she's giving away ho and helping others then she won't be able to survive much.

Charging into battle with the highest combined offenses of any physical blue unit (tied with Tana and Cordelia), along with very good defense, Lucina makes her presence known as soon as she enters the arena. What sets Lucina apart from other bulky units is her speed, which allows her to properly use that bulk as she rarely gets doubled. With Fury, she reaches a staggering base 37 attack (53 with her weapon), 39 speed, and 33 defense (with her weapon's defense boost)-with no iv's.

B-slot skill is mostly up to preference- since she can handle most red units at base, Lancebreaker can be used to guarantee the win against most blue units, while also cancelling out the lancebreaker that some mages typically run, allowing her to survive some encounters. Alternatively, one can run swordbreaker to catch all sword units, or vantage / quick riposte to perform better on the opponents phase.

Since Aether is a part of her base set, it works as a budget option while still providing the power if she needs it. As always, support and C-Slot skills are up to preference.

Firesweep and Moonbow
A:Sturdy Blow 2/Fury 3/Life or Death 3
B:Lancebreaker 3/ Swordbreaker 3
C:Spur Atk 3/Drive Atk3
Weapon: Firesweep Lance+
Support Skill: Repostion
Special: Moonbow