This one is courtesy of from the warp. It uses repeated line highlighting and washing to give a lightning like effect from the tip down the blade. Of course the colour could be varied or it could be done from the bottom up. This is another example from the warp. (images from the warp)
The NMM effect beloved by grey knights. This can look amazing but having looked around at how to do it I may be slightly out of my depth trying to replicate it. (image from Buypainted.com)
Necron style edge highlighting. This example is from Ieuan over at Sons of Isis and he's done a brilliant tutorial so I think that even I could follow it.
Plain silver. An oldy but a goody... (image from GW)
I'm leaning towards option 1 at the moment but would appreciate any other ideas or suggestions. So please feel free to voice your preference, give me some ideas or point me in the direction of something I've missed.....