Brave Weapons are weapons that have the word "Brave" in it, and allow attacks to occur twice during every combat. The following is a list of brave weapons.
I will be focusing on slower brave attackers. For Brave builds involving fast attackers, look at the Quad Brave. For Brave Bow, look at the guide Brave Bow and Luna.
The main aim of this build is to hit the enemy twice really really REALLY hard.
Passive Skill A
For this build, the only stat that truly matters is ATK. Skills that increases ATK by a larger amount would be very valuable in the build. This makes
Death Blow the premium choice for this build, as this build focuses on the player phase. Fire Boost also works if you could nuke anything without taking any damage.
For builds on a budget, the flat ATK+3 boost is a decent skill to work with.
Passive Skill B
This slot is largely dependent on play-style and preferences. For offensive options, breaker(e.g. Lancebreaker, G Tomebreaker) skills seem to make the most sense to combat characters of your own color more easily. However we want to focus on defensive options, as this build is better at nuking an enemy out of existence, and ensure that the character could either be totally safe, or at least be able to survive the enemy phase.
Wary Fighter makes a lot of sense for armored units, as it takes advantage of the unit's insane bulk, and armored units could out-duel units rather easily(even with the low MT from Brave weapons). Drag Back is also an option for every character to get the character out of safety more easily. For fliers specifically, Hit and Run might be preferred over Drag Back as it have lesser terrain requirements.
Special mentions to Wrath for Infantry users if you are opting for an offensive special. The additional 10 damage from getting into Wrath range could pack quite a punch. Furthermore the additional Wrath charge also allows quicker special charge, which meant ablity to run higher cooldown specials.
Passive Skill C
Similar to most Brave builds, skills that decrease the opponent's defenses are great, as these penalties are applied twice. Hence, Threaten Def is a very good option for the build, with Def Ploy also being a great option if your Brave user has respectable RES to utilize the skill.
Specials and Sacred Seal
The reason to lump these two together is because they pretty much come in a set.
The 2 main styles of play would be to either go for the standard 3-turn specials to activate on the second initiation (such as Draconic Aura), or go for the first-turn cheese with 1-turn cooldown specials (most notably Moonbow with the help of Quickened Pulse seal). The decision would largely depend on your team lineup and preferences.
This slot is not vital for the workings of this build. Hence for most cases, position-based skills works well.
The criteria for this build is very straightforward. You need your character to have as high of an ATK stat as possible. This meant that having an ATK boon for the character is of absolute necessity to maximize the potential for this build. The other stats are not as important, however having a decent bulk is a good trait to have if you are unable to pull your Brave user back to safety.
Reinhardt is the only magical unit capable of running this build, as Dire Thunder is a legendary tome with a Brave effect which cannot be inherited. However Reinhardt being a ranged unit means he could not use Drag Back or Hit and Run to get back to safety, and does not have the physical bulk to survive a hit. Be prepared with either a dancer or positioning skills to pull him out of danger.
The remaining units below are other examples that could utilise this build well. Note that this list is not meant to be exhaustive.