It could be considered a training knife, fidget device, or cyberpunk accessory, but the Shiny Knife is only made for one thing - looking cool in the dark.  Activate the blade by squeezing or locking the trigger.  Go somewhere dark, swing it, spin it, accidentally fling it into the background! 
 
Replaceable battery included.  Sheath has been discontinued in favor of single and double ring clips, sold here.