If I have a choice in a knife, I will always pick a bright color.
If I'm going to have it in the field, or by the garden, or in the woods, I'm probably going to drop it at some point. I'd like to be able to find it easily.
For guns, I don't have a strong preference, but I like blued and wood. I'd be hard pressed to pick between my Garand and my lever guns as to which I think is the best looking.
As to black guns- I'm fine with them. It's the opposite of knives though. I'm not likely to be dropping them, so I'd prefer they not stand out wherever I have them. No bright colors.
My wardrobe is much the same. If I have a bright color, it was given to me. (My wife loves when I wear my yellow shirt, for example.) I prefer dark reds, blues, browns, grays, etc...
I, too, am colorblind, but I just tend to memorize which shirt and pant combinations work. (And, owing to color choices, most of them work together, anyway.)