What was the first publication that documented that certain types of Drow weapons were destroyed by sunlight? I thought it was sometime in the AD&D D series of adventures for Greyhawk, but I've heard a claim that was a 2nd edition retcon. I'd like to know when this was first published and in what context.
While mentioned in the Monster Manual (1977) for Advanced Dungeons and Dragons, drow statistics aren't provided until Hall of the Fire Giant King (1978). The adventure module includes this Special Note Regarding Drow Cloaks, Armor, and Weapons:
All of these items have special properties, although none of them radiate any magic. The items are made under the conditions particular to the strange homeland of the Drow, for this place has unknown radiations which impart special properties to these cloaks, armor and weapons. When such items are exposed to direct sunlight a rotting process sets in. The process is absolutely irreversible, and within 2 week the cloaks will fall to shreds while the armor and weapons become pitted and unusable. If items are not exposed to sunlight, they will retain their magical properties for 31-50 days before losing them, and if they are exposed to the radiation of the Drow homeland 30 or so days, they will remain potent. Items not spoiled by sunlight will eventually lose their special properties if not exposed to the special radiation, but they will remain serviceable as normal cloaks, armor, shields, swords, maces, etc." (16)
The note then details the effects of sunlight on drow sleep poison. The module by 1981 had become the third part of Against the Giants, and includes the same note. The Fiend Folio (1981) in its Elf--Drow entry includes a similar note.