Flaw with the Skin item system
I am led to beleive the zenith weapons and the skins from achievements are unlocked, and once you have unlocked one you can access it as often as you like, like the HOM skins obtained from playing GW1. Will see when the 1st is obtained either today or tomorrow anyway.
On the other hand I kind of agree on the other hand the limited edition skins (Jade and Sclerite especially) seem hard to obtain for those who exclusively PvP.