I bought one several years back and it was useless. It did nothing to help blood stand out more. Since you are color blind it could help though, I would give it a shoot and see.
I don't know the black light will actually work, but I know you can get them in flashlights and they work well! I have one and I believe it's actually used to find scorpions because the glow under black light
Those lights are crummy. They do make blood kind of stand out but they also make every leaf on the ground glow, so it is very difficult still to discern what is and isn't blood. If you can't see the blood I suggest you try hydrogen peroxide, it makes the blood turn bright white and foam. https://www.youtube.com/watch?v=MTTMhEX9U_w
