Adamantite: +499 CF. Cannot be combined with Baatorian Green Steel, Meteoric, Mithril, or Orichalcum. Cutting and impaling weapons gain an armor divisor of (2), which stacks with enchantment, allowing an improvement by one step. Adamantite weapons won't break.

Baatorian Green Steel: 0.6 times weight and minimum +3 CF, probably more. Extremely rare, as it comes from Baator, on the Outer Planes. Cannot be combined with Adamantite, Meteoric, Mithril, or Orichalcum. Cutting and impaling weapons gain +1 damage per die. All weapons gain -2 to Minimum ST.

Drow: Drow made weapons are naturally enchanted by years of exposure to Underdark radiation. These weapons give a bonus to skill and damage with the weapon up to +5, but may not be further enchanted to improve these characteristics. Unfortunately, they weaken when exposed to sunlight, reducing the bonus by 1 per day until it's gone. After that, the weapon gains +2 to odds of breakage per day thereafter until it's useless. If combined with Adamantite or the Shatterproof enchantment, it becomes possible to break the weapon the first day after it's bonus fades and thereafter gains +2 to odds of breakage each day. +10 CF x (bonus squared).

Mithril: +299 CF. Cannot be combined with Adamantite, Baatorian Green Steel, Meteoric or Orichalcum. -2 to odds of breakage and +1 to damage for any cutting or impaling weapon, but can never benefit from the use of a Dwarven Whetstone (see p. DF1:25).