Fallen Warrior Manteau drop in the Bio 5: The Bed of Honor Dungeon from the MVPs.
There are two versions of Fallen Warrior Manteau:

• Fallen Warrior Manteau (20748) has no card slot and no bonuses to MaxHP and MaxSP. These drop from Tomb of the Fallen MVPs at a 75% chance.
• Fallen Warrior Manteau [1] (20749) has a card slot and provides additional MaxHP and MaxSP bonuses. These must be upgraded from the above version.

To upgrade a Fallen Warrior Manteau (20748) to its slotted version, you need to speak with Sorrowful Soul's Energy (near (lhz_dun_n 136, 265)).

There is a 30% chance of success and, in case of failure, everything will be lost:

• 1 Fallen Warrior Manteau (20748)
  
• 20 Ghost Chill (6471)
  
• 100 Energy Fragment (6820)
  

You can also opt for a safe upgrade option that has no chance of failure:

• 1 Fallen Warrior Manteau (20748)
  
• 100 Ghost Chill (6471)
  
• 500 Energy Fragment (6820)
  

Note: Any refines on the item will be lost in either process.

Fallen Warrior Manteau can be cominated with the Vicious Mind Aura.

Item	Description	+	Item	Description
Fallen Warrior Manteau (20748)	Manteau of legendary hero whose died in battle. ─────────── Base STR at least 90: ATK +10 ─────────── For each Refine Level: ATK +2 ─────────── Base INT at least 90: MATK +20 ─────────── For each Refine Level: MATK +3 ─────────── Base VIT at least 90: Decreases damage taken from Neutral elemental attacks by 3%. ─────────── Refine Level +8: Decreases damage taken from Neutral elemental attacks by 3%. ─────────── Refine Level +10: Decreases damage taken from Neutral elemental attacks by 4%. ─────────── Base AGI at least 90: Decreases After Attack Delay by 3%. ─────────── For each 2 Refine Levels: Decreases After Attack Delay by 1%. ─────────── Refine Level +10: ASPD +1 ─────────── Base DEX at least 90: Increases Ranged Physical Damage by 3%. ─────────── For each 2 Refine Levels: Increases Ranged Physical Damage by 1%. ─────────── Base LUK at least 90: Increases Critical Damage by 5%. ─────────── For each Refine Level: Increases Critical Damage by 1%. ─────────── Type: Armor Position: Garment Defense: 20 Armor Level: 1 Refinable Weight: 60 Required Level: 120		Vicious Mind Aura (19439)	Unknown energy surrounds the body. ─────────── When equipped with Fallen Warrior Manteau[1]: ─────────── For each 30 base STR: ATK +5 ─────────── For each 30 base AGI: Increases Attack Speed by 3%. ─────────── For each 30 base VIT: Decreases After Cast Delay by 4%. ─────────── For each 30 base INT: MATK +5 Decreases Variable Casting Time by 8%. ─────────── For each 30 base DEX: Increases Ranged Physical Damage by 1%. ─────────── For each 30 base LUK: Increases Critical Damage by 3%. ─────────── Type: Armor Position: Head Low Defense: 5 Armor Level: 1 Weight: 10 Required Level: 170

Vicious Mind Aura is part of the Bioresearch Laboratory - Instance.