Fitted to the back of the hand or worn as a glove, a Riveblade is covered in a shimmering energy field which can punch through the thickest armour. In the hands of a Harlequin a set of Riveblades can be used to behead or disembowel the target with a single sweep. A Harlequin with Riveblades ignores normal armour saves in an assault. There is an additional effect against target's with multiple wounds. If such a model is wounded with a roll of a 6 the Riveblades have penetrated deep into their body and they are killed outright (unless the model has an invulnerable saving throw which is passed). Riveblades cannot be combined with power blades.
Riveblades
Source: Codex: Harlequins, p. 12