"The ulaks had first been forged by the ancient monks, used in defense of honor."
Riddick musing about ulaks on Aguerra Prime.

Ulaks are curved single-edged knives with serrated edges, typically used in tandem. They were apparently created by ancient monks of a sort, an order that Riddick was familiar with. One of the guards at the penal colony on Crematoria was in possession of a pair of these knives.