One point which (I think) hasn't been brought up yet about using blacked out tactical knives is that if it's hard to see by your 'enemy', then it's hard to see by you too.

3 of my favorite knives are coated/plated/whatever and are black and/or very dark (not one of the reasons I bought them though they do look cool so that may have influenced my macho-ness subconciously). All of those knives have a bright yellow/reflective wrist cord or handle wrap because no matter how careful you are you're going to drop it or set it down sooner or later and if it's pitch black out, it might not matter how bright your light is. If I had to find my LMF II in the bush after dropping it in fall leaves, I could be looking a LONG time and likely wouldn't find it until I cut myself on it.

That being said I can see it being desirable to be low key even in the civilian world. I carry at least one knife everywhere I go...sometimes it's a sizable one. If I need to pull it out, the fewer people who notice, the better...I don't want people's eyes drawn to why I've whipped it out as I could be doing something as simple as cutting rope but perception is 9/10th of the law and a simple task to me could be psychopathic tendancies to those around me who don't know me. In this day and age of paranoia, that's the only enemy I'm worried about.