The Gesen Bow requires a minimum Strength of 3 to use and can't be used by Clerics, Druids or Mages. It grants a +4 THAC0 bonus, inflicts 2 Piercing damage + 1D8 Electrical damage per hit, creates an infinite supply of ammunition, and provides the wielding with +20% Electrical Resistance.
If no arrows are equipped, the bow will fire its innate +4 arrows - an unique feature, as normal arrows can only have up to +3 enchantment. This means it can be used against powerful enemies where other bows would fail, such as Demi-Liches.
Any other types of arrows fired from the bow will have "2 piercing + 1D8 electrical" added to their damage value, but their original enchantment value will not be changed.
In-game description Edit
"The finest bow crafted by Gesen Khan, this weapon draws energy from another plane, firing spears of lightning instead of arrows... and therefore never requiring ammunition of any kind. It is said that Gesen prepared to retire from his craft after selling the invaluable weapon, only to have the bow wrested from his grasp by a thief who used it to end Gesen's own life. A side effect of the bow bestows protection from electricity upon the user."