Here is me and the setup I retired with although the tasers are finally being replaced by black ones. You'll see a large TDI KaBar tanto knife behind sticking out right above it so that pretty much summarizes my view of cops with knives. I mounted the knife there so I can grab it during gun takeaway defense. Some guys like the handle facing the other way so they they can grab it off hand which is fine too.
The problem with knives is a perception issue with skittish administrations. I would a third of the departments would not allow my set up and some wouldn't allow that knife even concealed. You can shoot someone but don't stab them because that's barbaric. Conversly don't shoot someone stabbing you because it's only a knife....