The Crozius Arcanum is a mace or staff that is used as both a melee weapon and the primary badge of office of Space Marine Chaplains. This duality of purpose presents no philosophical conundrum for the Chaplains, as for them battle itself represents the most valuable form of worship of the Emperor of Mankind. It is normally shaped in the form of either a staff or a mace topped by the double-headed Aquila of the Imperium or a winged skull that represents the Emperor's sacrifice. A few versions use iconography from the Chapter they belong to, such as the blacksmith's hammer-version used by some Chaplains from the Salamanders Chapter. Chaplain Cassius, the Master of Sanctity (chief Chaplain) of the Ultramarines Chapter, has fashioned his Crozius Arcanum in the form of a Tyranid head, in remembrance of Hive Fleet Behemoth's costly invasion of their homeworld of Macragge during the First Tyrannic War. Incorporated within the shaft of the Crozius is a powerful gravitic energy field capable of disrupting matter much in the same way as a Power Weapon. The Crozius is the badge of office of Chaplains and is normally used in many Space Marine ceremonies and rituals across a vast array of Chapters. To show their faith in the Emperor of Mankind, the Crozius, along with the Chaplain, is most likely to be adorned by Purity Seals and other tokens of faith.
The Crozius Arcanum is still used by the corrupted Dark Apostles of the Word Bearers, which is the only Chaos Space Marine Traitor Legion still to employ the use of Chaplains. However, in the hands of the Dark Apostles, the weapon is known as an Accursed Crozius, now a symbol of the Dark Apostles' devotion to the Ruinous Powers of Chaos in the form of the Chaos Star, rather than a sacred emblem of their reverence for the Emperor. Not only is the Accursed Crozius still a potent weapon, it also signifies that its bearer is blessed by the Chaos Gods, enjoying physical protection as well as a closer connection to and ability to summon the Daemons of the Warp. At the time of the Horus Heresy, most of the Chaplains of the Traitor Legions resisted the lure of Chaos and were slaughtered by their fellow Space Marines, though the Chaplains of the Word Bearers were as possessed of the same fervent desire to find entities truly worthy of worship as their Primarch Lorgar and so they willingly followed him into devotion to Chaos Undivided. To prove their dedication to faith to the Ruinous Powers, the Chaplains corrupted their once-sacred Crozius Arcanum, a symbol of the Imperial Truth that they had now abandoned. In battle, the Accursed Crozius now serves not only as both a weapon and mark of a Dark Apostles' rank, but also a powerful link between the bearer and the entities of the Warp itself.
- Codex: Space Marines (4th Edition)
- Codex: Space Marines (5th Edition)
- Codex: Chaos Space Marines (4th Edition)
- Warhammer 40,000: Wargear