Sa...Wha...Is it stranger that you can butcher sentients or that you can make swords out of brains?
Also, how?
Actually, it appears you don't have to butcher them to make swords out of their brains. It seems the game randomly grabs a material from the body. So if you use a severed head, you'll likely get brains as a material. Surprisingly sharp.
The worst part was the guy used to be my companion. Hohoho.
And, since you asked so nicely, here's how.
reaction_survival
[OBJECT:REACTION]
[REACTION:MAKE_QUIVER]
[NAME:make quiver]
[ADVENTURE_MODE_ENABLED]
[REAGENT:corpse piece:1:CORPSEPIECE:NONE:NONE:NONE]
[PRODUCT:100:1:QUIVER:NONE:GET_MATERIAL_FROM_REAGENT:corpse piece:NONE]
[SKILL:KNAPPING]
[REACTION:MAKE_BACKPACK]
[NAME:make backpack]
[ADVENTURE_MODE_ENABLED]
[REAGENT:corpse piece:1:CORPSEPIECE:NONE:NONE:NONE]
[PRODUCT:100:1:BACKPACK:NONE:GET_MATERIAL_FROM_REAGENT:corpse piece:NONE]
[SKILL:KNAPPING]
[REACTION:MAKE_CROWN]
[NAME:make crown]
[ADVENTURE_MODE_ENABLED]
[REAGENT:corpse piece:1:CORPSEPIECE:NONE:NONE:NONE]
[PRODUCT:100:1:CROWN:NONE:GET_MATERIAL_FROM_REAGENT:corpse piece:NONE]
[SKILL:KNAPPING]
[REACTION:MAKE_AMMO]
[NAME:make arrows]
[ADVENTURE_MODE_ENABLED]
[REAGENT:corpse piece:1:CORPSEPIECE:NONE:NONE:NONE]
[PRODUCT:100:25:AMMO:ITEM_AMMO_ARROWS:GET_MATERIAL_FROM_REAGENT:corpse piece:NONE][FORCE_EDGE]
[SKILL:KNAPPING]
[REACTION:MAKE_SWORD]
[NAME:make long sword]
[ADVENTURE_MODE_ENABLED]
[REAGENT:corpse piece:1:CORPSEPIECE:NONE:NONE:NONE]
[PRODUCT:100:1:WEAPON:ITEM_WEAPON_SWORD_LONG:GET_MATERIAL_FROM_REAGENT:corpse piece:NONE][FORCE_EDGE]
[SKILL:KNAPPING]
[REACTION:MAKE_HALBERD]
[NAME:make halberd]
[ADVENTURE_MODE_ENABLED]
[REAGENT:corpse piece:1:CORPSEPIECE:NONE:NONE:NONE]
[PRODUCT:100:1:WEAPON:ITEM_WEAPON_HALBERD:GET_MATERIAL_FROM_REAGENT:corpse piece:NONE][FORCE_EDGE]
[SKILL:KNAPPING]
Just remember, this raw file was only an experiment into knapping. I take no responsibility on anything anyone does with this, or what this does to you.