Light Kunai - Lightsaber Throwing Spikes 

same

Pravin Kaliyugavarathan thats so easy i did that. You just have to get one of those lightsabers that folds up, cut off the last two pieces, then attach it to your arm.

Or how to make the holster?

+Ivan Boroda Aside from the obvious ninja aesthetics, I can think of a few good reasons for the side blades for this particular design/implementation of a Lightsaber. 1) Defense and Battery Life Limitation The original protosabers had external battery packs due to battery life issues. "Current" lightsabers do not need said large external batteries due to only using energy when hitting/interacting with another object. However, the cells would still need to be changed/recharged "periodically". Due to the very, very small size of the Light Kunai, you could assume that it would be possible that if used repeatedly for defense in a long fight, the energy cells could fail. So having Phrik, Songsteel, Ultrachrome or Mando Iron blades on the sides would be very "handy" to avoid losing another arm in a fight. 2) Poison/Bleeding Ninjas often used poisons on their weapons to kill targets without getting a fatal strike. Getting poison into the bloodstream seems unlikely with a traditional lightsaber since the wound would instantly cauterize not to mention coating a magnetically captured high energy light plasma beam in poison seems... unlikely. The Lightblade part of the Kunai would act to cripple as well as create a "pilot hole" for the blades penetration (especially through armor) and the side blades would create lingering, bleeding wounds that could also have been poisoned. 3)Flight Stabilization Kunai and throwing weapons have a certain weight and geometry to aid in flight. Matching those would mean someone trained to throw traditional Kunai could easily use the Light Kunai. The Blades on the front shift the center of mass forward toward the center of the weapon and might act like wee control surfaces/wings during flight. So instead of assuming anything you don't understand is wrong, I'd say try to assume others just might have actually put some thought into the things they create.

+Ivan Boroda Would you like ice with that burn?

Probably mainly for balance. Lightsabers probably don't have a whole lot of mass associated with them, so the blades act as flight stabilizers. *shrug*