Athame

Athames are Astartes combat blades carried by the followers of the Prophet of Light. They are based on weapons first created by Erebus of the Word Bearers during the Horus Heresy. Each Chapter or Host has its own distinct design. The Sons of Xandor, for example, have athames that look almost exactly like M30 "Crusade" pattern knives, while the Red Brethren's athames look like skinning blades. Each blade is hand-forged by the Chapter's sorcerers, and given to each acolyte that makes initiate rank.

The essence of the weapon is the same regardless: a serrated blade, made out of dark flint or similar stone. A seemingly primitive weapon, the athame is subtly infused with the essence of the warp. It is nearly unbreakable, and is about as effective as a Mechanicus-forged blade against heavy armor (not ideal, but can work in a pinch). It's true value, however, is that it can harm the denizens of the Warp.

Some athames have additional powers, either by design (during the forging process) or abilities accumulated through use (it's said that any being slain by an athame leaves a piece of its soul in the blade). Sorcerers frequently use their athames as foci during rituals and summonings.