Why did I know a gunblade (or should it be blastersaber?) would pop up.
Okay, one render it'll be.
EDIT: For anyone who is interested, for blades, the core is white (with a very, very subtle tint due to the colour of the blade but this is only visible on the strongest colours such as deep reds and purples) with the coloured glow around it. To get this effect, the easiest way is to change the blade's luminosity (the armount that the surface is lit regarless of what light falls on it) to way above normal. At least 100% (if your program uses % scales) if not a little more. This should saturate out the colour and make the material white regardless of the material's base colour or texture. Hopefully, your glow should stay the same as the base colour (this should be the case in MAX and, apparently, newer versions of Lightwave), if not you'll need to change the glow settings or do some after effects work.
There are some more complex methods that involve volumetric rendering and some particle effects, but it's fiddly work, it's best just to work on the saber itself and leave the blade switched off.