Humour is the main stat of the Weaver. Humour is heavily involved in the Resistance and Resilience branches, and unlocks many dialogue options making use of cruel irony or dark comedy. The first example of this is The Heroine stating that hallucinating her mother's voice in the room next to her father's corpse technically makes the occasion a family reunion.
Humour increases Absorption, which directly subtracts damage done by enemies. For example, having an Absorption of 50 means that if you were hit for 64 damage, you would only receive 14. If the numbers were reversed, the damage would be completely negated.
This can be seen as The Heroine making light of grave situations, meaning that the insults and traumas made by her enemies have less of an effect on her, though that her blindness to her past causes her pain later.