During ALL updates back in day, they were dropping Sgs at the moment. Maybe, when they added Kree'arra and so on, then changed to AGS. Dunno. Postponed playing by then. Didn't knew at all, cause Emps servers were so lagging and DC's happened a lot to most of the players, which lead to some of them retiring.
It was definitely ags.
I'm telling you about drops that have been when I played, it was SGS, which means it really was SGS, and not AGS. Maybe, when you joined the game they probably already changed unique drop to AGS. Discussion over. I'm aware that we should stay O-T, before this escalates into deeper buzz.
O-T: I agree with this suggestion, as long as Crystal Halberd or all its parts is implemented to Skeletal Wyvern, logically it is one of the best choice, having in mind, that Wyverns are only monster to drop Crystal Items, excluding Crystal Key parts or Crystal key.