More real knife fights happened in bars vs in combat.
Even then most of the fights were one-sided where the opposing fighter saw he was out-matched by a more skilled combatant, or a combatant who appeared to be more skilled, (or had a bigger knife). A knife fighter makes an excellent target (for most hand guys) if the person with the hand gun is not taken by surprise.

A couple of links to about the 21 foot rule ie Gun/Knife "combat".

http://www.policemag.com/channel/weapons/articles/2014/09/revisiting-the-21-foot-rule.aspx

"Whether the "21-Foot Rule" is an applicable defense in an officer-involved shooting actually depends upon the facts and evidence of each case."

This video shows the difference between a surprise attack and the LEO being aware.

https://www.youtube.com/watch?v=J_KJ1R2PCMM

https://www.policeone.com/close-quarters...e-valid-Part-2/

So if the opposing soldier were taken by surprise by a "knife guy" in a specific unit possibly there would be some 'micro' basis for leaving the blood on the knife vs cleaning the blade (as a bragging point).

Tom V.

Personally I say BS.