from Star Trek Klingon, the interactive CD.
Time stop 00 06 00
Who was the killer? Hey, I know! Let's ask Vok, maybe he'll kn... wha .. DAMNIT QUALON!!

This episode refers to a blood oath, which was introduced in an episode aptly titled "Blood Oath" (Deep Space Nine, Season 2, Episode 19 March 27, 1994) in which we see 3 Klingon characters/actors from the original 1960's Star Trek shows.

Also of note, "Blood Oath" shows klingon blood to be red and watery like ours, not purple and gloppy like here and in Star Trek VI: The Undiscovered Country (1991). My theory on that is that Simon Shuster were worried about blood and violence. This would also explain why Voq getting stabbed was shot from behind a chickenwire wall.