Rainbird on 16 October 2010
So it is purely cosmetic then, I'll change the OP. 
EDIT: Actually, it's not purely cosmetic I've just remembered. It's not the first time videogame websites get it wrong, but here is how it works:
"John: Yes, each weapon and piece of armor has inherent bonuses as well as an open slot that an upgrade component can be applied to for extra bonuses. The types of upgrade components will vary depending on the item; for instance, a crest is an upgrade component that is used to enhance light armor pieces."
http://www.arena.net/blog/john-and-eric-answer-your-items-and-loot-questions
