Weapon dye issues

I'm trying to dye my blue air wand and my blue storm artifact green. Now, when I use green dye on the wand, it turns reddish brown, and when I use it on the storm artifact it turns an ugly shade of light aquamarine. Now, this was expected, because I know armor dyes way better than anything else. I also tried using Blue->Green mixed dye on the storm artifact, and it turned a sort of ugly brown too.

So, is there any way I can figure out which color I'd need to make them green, without massive amounts of experimentation?

use dye remover on them first, then dye them. Some items come pre-dyed, but instead of over-writing the color, new dye acts like mixing the dyes.