From Lexicanum

The Warp Blade is a Daemon Weapon of Tzeentch.^{1-p61 2}

Overview

The Warp Blade is gifted by Tzeentch to his mightiest servants. It has the power to dissipate and scatter psychic energy directed towards it, as well as being a highly potent close combat weapon. However, its power tends to attract the attention of Daemons.^1-p61

Sources

• ¹:Codex: Chaos Space Marines (3rd Edition, 2nd Codex), p61
• ²:Warhammer 40,000: Wargear