Q: I remember in the 1st and 2nd editions that drow items were destroyed when exposed to sunlight. I have checked the Player’s Handbook, DMG and the Monster Manual, and haven't found anything specifying this. Is this still one of rules?
A: Indeed, from the 1st edition Fiend Folio, in which drow appeared (following their introduction within module G3: Hall of the Fire Giant Chief, and subsequent adventures):
Special Note Regarding Drow Treasure: Cloaks, armor, and weapons made by the Drow have special properties, although they do not radiate magic. The items are made in the strange homeland of the Drow: vast underground cities of carven stone and minerals, places of weird and fantastic beauty inundated with unknown radiations which impart the special properties to their items. When these are exposed to direct sunlight, irreversible decay starts and the items will become totally useless in 2-12 days. If protected from sunlight, they will retain their special properties for 31-50 days before becoming normal items; and if exposed to the radiations of the Drow homeland for a period of 1 week out of every 4 weeks, the items could remain potent indefinitely. Drow sleep poison decays instantly in sunlight, and will lose its effectiveness after 60 days in any event after being exposed to air, although unopened packets of the poison will remain potent for up to one year.
At the time, this prevented characters from returning to the surface with powerful drow weapons (including the beloved hand crossbow), armor and poison. For those of you familiar with R.A. Salvatore’s books, this happened to Drizzt Do'Urden’s gear when he migrated to the surface world.
For DMs interested in retaining this property, look no further than pg. 68 of the Underdark sourcebook. "Drowcraft" is a special property that weapons may have, and speak to their former incarnation: "Drowcraft weapons were once quite common, but they have fallen out of favor in some drow cities. A drowcraft weapon is energized by local earth nodes and the surrounding aura of faerzress. As long as it remains within an earth node or zone of faerzress, it grants its wielder a +2 luck bonus on attack and damage rolls, in addition to its normal enhancement bonus. Outside a faerzress zone (for example, aboveground), the weapon does not grant the luck bonus, but it otherwise works normally. A drowcraft weapon exposed to sunlight must make a DC 8 Fort save or dissolve utterly. A new save at the same DC is required for each day of exposure. Sheathed weapons or weapons exposed to indirect light (such as indoors) are still vulnerable to this effect, but a drowcraft weapon can be kept safe indefinitely inside a lead-lined case."