It depends on the wavelength. The deeper into that end of the spectrum the worse on your eye. I have several 1watt cree uv xlamps which are around 395nm, but am not familiar with yours. The black lights at night clubs are fluourescent near UV, and not as focused as what you'll probably see in a flashlight.
You do need to be careful about using that on reflective surfaces. The best is to use some cheap yellow safety or shooting glasses. These are very inexpensive, will almost all of the UV, and the color will provide a sharper distinction between what is fluourescing and what is simply reflecting. Even if you don't care about safety and your eyes, the yellow glasses will help you see better with these leds.