Oh you gotta love Ebay. When someone said that you can 99% of things under the sun at Ebay, they were never more correct.
This particular auction for the energy sword on Ebay, is a 4 foot long replica of the Halo Plasma sword. The sword is lit up with Blue Sapphire lights, comes with its own wall charger and has an on/off switch in the handle. The dude making these also makes needlers and plasma rifles. You cannot help but be impressed. Perfect for Halloween. Now I need to get one of those Master Chief costumes.