Honor was an Ability Score used in Oriental Adventures (1985). It could be used in the place of Charisma or Comeliness on certain rolls. It was a number generated based on a character's race, character class, social class, and alignment. It favored the Lawful and Good alignments over the Chaotic and Evil alignments.
The player had to roll for their character's base Honor level on a chart that was based on . Characters with low Honor could improve their score by noble or pious actions, which gave Honor Points. Honor Points could be collected to go up an Honor Level or might be lost to reduce a character's Honor Level. Losing 5 or more Honor points at a time reduced a character by a full Honor level.
What was unclear was that Ninja (assassins) and Yakuza (thieves) had their own honor codes that were different from Samurai (paladin-equivalents) and Kensai (duelists). The rules made it harder for "dishonorable" character classes to progress under the Honor rules. There were few examples of actions that would gain Honor points and many that could lose them.
There was also an inherited Clan or family honor and family tree, with NPC relatives that might disgrace or improve a family's collective Honor. If a character had an Honor score lower than their Clan's collective Honor score, they would suffer a modifier on reactions until they met or exceeded that score.