Page 104 has at least 5 paragraphs about the drink, in the Spellbound book.
The drink is a drug (least I would say it would be according to 3E), that gives Rashemen different effects, some good, some bad.
Here's what was in that book.
XP Value: None
The dark reddish brew (not to be confused with the Old Empires drink called firewine) is made by the witches from grapes and fruits specially grown on plantations near the city of Urling, with various herbs added for increased potency. While it is not truely an enchanted item, its effects are certainly close.
Jhuild is generally considered to be the national drink of Rashemen. The land's berserkers are said to consume considerable quanties of firewine before going into battle, and it is said to both increase ferocity and bolster morale.
Each pint of Jhuild consumed has the following effect: It increases morale level of NPC's by 1 (maximum increase of 5), decreases wisdom by 1 (max decrease of 5, to a min of 1, and adds +1 to all damage rolls - all for 2d4 hours after consumption. These effects may be avoided with a successful Con roll, but the roll must be made for each pint seperately, and is at a cumulative penalty of -1 for each pint consumed.
Once the 2d4 hour perio has elasped, the drinker immediately falls into a deep sleep for 3d4 hours and awaked with a throbbing head, thick tongue, and a miserable desire to crawl under a rock. This is all considered part of the price the Rashemar pay for being the fiercest warriors in Faerun, and no one complains (at least not much).
Firewine sells for 1 GP per pint in Rashemen and at least 15 GP per point in other lands, with the price increasing the farther one goes from the land of the berserkers. A single bottle of Jhuild, containing about two quarts, is said to have brought 100 GP at an auction in Waterdeep, for example.