瀉火

Missing, extremely new, or very obvious to obtain.

Heatiness is a concept in Traditional Chinese Medicine that is used to describe the body in a state of excessive heat, which makes the person more irritable. The Shell of Faded Rage's whole theme is anger, as mentioned in its info. So, the achievement wants players to purge (Weakness Break) the heatiness (Obscure Blaze, which contributes to more hits in Bonpiercing Odium, and odium is general widespread hatred or disgust) within the meme.