Screen captures courtesy of Earth62.net
First, a special thanks to the poster Eradicator from the MCA Sliders forum for pointing this out.
The knife prominently featured in "Common Ground" and very briefly in "Slidecage" is avaiable to the mass market under the name "Raptor". This blade was crafted by Gill Hibben and has been mass marketed by United Cutlery, and the knife was marketed based on its use in the Mortal Kombat movie. Despite this MK branding, the knife has appeared in several other productions (including as a Klingon dagger on Star Trek: Deep Space Nine).
The knife can be found at several on-line stores, including GungFu.com and GunAccessories.com.