nom6d, the blue sparks are created by the .fx file you are using. I am guessing you are running entik.fx? easy way to check is find
cg_fxfile "entik.fx"
You now need to open entik.fx (using notepad++, wordpad etc) and scroll to near the bottom where you will find lightning (ctrl+f "lightning"). If you are using entik.fx you will see pretty much this exact paragraph:
Code:
//blue Sparks
shader flareShader
alpha 0.9
color 0.3 0.4 0.6
repeat 2 {
wobble dir velocity 10 + rand*20
scale velocity velocity 150 + rand*50
size 2 + rand*2
emitter 0.7 + rand*0.1 {
colorFade 0.01
Sprite
moveBounce 400 0.7
}
}
You want to delete this paragraph AND ONLY THIS PARAGRAPH. Either that, or change:
leave the rest of lightning alone 
You might want to backup entik.fx first 
Thanks for the idea guys, but cl_useq3gibs is already 0...as is cg_blood and com_blood