in game\gui\window_character.gui file : you'd find this block of script, setting the green and red glow for the trait icons.
Code:
item = {
container = {
icon_trait = {
visible = "[Not(Character.GetFaith.IsTraitSin( Trait.Self ))]"
blockoverride "icon_size"
{
size = { 55 55 }
}
blockoverride "glow" {
glow = {
visible = "[Character.GetFaith.IsTraitVirtue( Trait.Self )]"
using = Color_Green
glow_radius = 5
using = Glow_Standard
}
}
}
icon_trait = {
visible = "[Character.GetFaith.IsTraitSin( Trait.Self )]"
blockoverride "icon_size"
{
size = { 55 55 }
}
blockoverride "glow" {
glow = {
using = Color_Red
glow_radius = 5
using = Glow_Standard
}
}
}
}
}
Not sure where exactly you can find a list of possible colours for these, or if you can set some new ones.