I'd say they forgot to add Summoner armors per usual. I don't know how you can make a MMO from 2001 to 2011 and still not understand that a Summoner does not use enfeebling magic and needs a real armor and not a generic mage armor.

At least I can sit here and laugh together with the PUPs who also got the same armor set. Jolly good time PUPs, enjoying the elemental skill bonuses much?