It introduces weapons that have histories and abilities matching their history, as well as rules governing such weapons in a campaign.
Legacy Weapons
Legacy weapons are unique weapons that have been forged or used by legendary beings and are themselves unique in regards to gameplay in that their magical abilities start out locked. Unlocking them requires some sort of sacrifice on the part of the wielder, in varying amounts, referred to as least legacy, lesser legacy, and greater legacy, in order from weakest to strongest.
The sacrifices required vary with each weapon, but they include some sort of permanent reduction in a player's abilities, i.e. loss of maximum hit points, permanent penalties to certain skills or abilities, etc. These penalties end when the wielder forswears the weapon.
If a wielder of a legacy weapon defeats the wielder of a different legacy weapon or artifact with it in combat, the winning legacy weapon inherits an ability from the defeated foe's legacy weapon/artifact.
