Actually - according to what Giles emailed me late last night - he wouldn't have had to visit Angel to diagnose because he has seen it all before. And to explain why he wouldn't have mentioned it to Xander, he could have (a) assumed Xander would know because he doesn't know where in the Buffy timeline Xander came from (from Xander) or (b) because Xander didn't ask (from Giles).

So, while I was vague when V talked to Bel & Logan, I think we can operate on the assumption that he did, in fact, tell V & Cordy the name of the poison (which is escaping me at this particular moment). We won't get that scene done until I get home from work though - so we could really have it go either way - up to you :)