I wanted a glowing bladed knife for a sci-fi cosplay costume. So I designed this one. I used the handle from Herman_Lundgren's Bayonet (CS:GO Knife) http://www.thingiverse.com/thi..., because I felt it had the right sort of military sci-fi look.

It is designed to fit the common 20.5cm by 0.5cm (8"x1/4") glow sticks, which I get in packs of 50 for a few dollars. They are the ones used to make necklaces and bracelets. They just slip in the hole in the base, and press into the socket at the tip. I find they are a close enough fit that they don't move about, but if needed you could just wrap a bit of sticky tape around the end of the glowstick, and it should hold it in place quite securely.

The plastic doesn't quite transmit as much light as I would like, but if you put the glowstick in boiling water before breaking it, they can be very bright.

This is a prop, It doesn't have an edge, and will likely break if you tried to stab someone.

I printed this upright with a 30 line brim in PLA at 205 degree nozzle and 55 degree bed.   I printed it at 100% scale. on my Wombot XL, with no rafts or supports with 0.05mm layers and 20% infill.