It has been already been asked in the “Asura” forum (LINK).
Please, add a “lighting” color slot for the Savant Armor (asura T3 light racial armor). We want to be able to dye our coat on a different color of the lighting on our armor, just like Kudu!
[img]http://wiki.guildwars2.com/images/thumb/d/dc/Kudu.png/381px-Kudu.png[/img]
We know it’s possible (as seen in the image above) and it shouldn’t be too hard to implement. 
Please give the asura (almost 90% of asura light-armor users wear this) a little more room for customization! 
Asura Savant armor - 4th color slot
Kudu’s isn’t a Light armor, though. His is medium (as he’s an Engineer) and it has the armguard on the left arm, not the right.