Glass knife
A close-combat weapon of Xeno origin, the Fra'al glass knife was recovered from Obsidian station after a particularly hostile Xeno attack, where it was handed over to the Ordo Xenos for examination. Upon closer inspection, the knife appears to be made from an unknown mineral, almost certainly as hard as diamond whilst as strong as if it were made from titanium. The edges of the blade constantly stay sharp, as microfractures constantly cause tiny shards to fracture away. These splinters also have the side-effect of working their way into wounds and causing agonising pain. Attempts to replicate such a weapon for the Imperial Guard are currently underway by the Inquisition and Adeptus Mechanicus.