Technically, there's two new lightsabers, one using the old viridian from K2 and renaming it jade, and a neatish looking red blade with a silver glow. The new viridian is a recolor and works by overriding. So, two new lightsabers but three new blades.
Get them at PC Game Mods (
http://www.pcgamemods.com/mod/18705.html) or at my site (
http://www.princessartemis.com/images/mods/k2virid.html), along with screenshots and most of the readme.
I dunno about anyone else, but when I first started playing K2 and realized there were viridian lightsabers, I was excited. Viridian, next to Alizarin Crimson, is my favorite oil color. I was actually offended when I saw what they passed off as viridian in K2. It's...chartruese. Spring-green. Something that could never be viridian.
So here I am, trying to fix it. It's still not quite viridian, but it's as dark a green as I can get right now without making a black 'saber. There's nothing special about the hilts--this is purely a re-texture, although I needed to make custom lightsabers with color crystals to use the colors.
They're compatible with USM as long as USM was installed first.
Cheat in the new bloodstone/hematite lightsaber by using g_w_lghtsbr77, etc. Jade (the original TSL viridian) is g_w_lghtsbr78. They come in short and double varieties as well. The color crystals are u_l_colo_77 and u_l_colo_78. No need to cheat in viridian, although if you want to, they're g_w_lghtsbr11 and u_l_colo_9 as I recall.
This also replaces the viridian lightsaber .uti with a more appropriate looking crystal and description, switching out the original viridian so it's now the jade crystal.