it isnt special glow...you can edit length and anythink about glows in weapongrp.dat for example
LineageEffect.c_u004 0.000000 0.000000 0.000000 0.600000 0.100000
The 5 numbers after effect define a few things.
1st number = position on the weapon [how close to the handle, or tip of the blade.
2nd number = vertical position relative to you [so it will move off the blade up or down]
3rd = horizontal position relative to you [so it will move off the blade side ways.]
4th = is how "fat" it will be.
5th = how long it will be.