From Dragon 318, which updated Rokugan/Oriental Adventures material to 3.5.
Silver Tongue [Dragon]: You can use the Diplomacy skill (trained or untrained) to produce the following effects:
Change an NPC's attitude toward a person other than yourself. The DC is the same as if you were changing the character's attitude toward you.
Inspire love and devotion. If you successfully improve a character's attitude toward you (only) to helpful, you can choose to cause that character to show romantic interest in you. The character thereafter seeks every opportunity to be near you and makes every effort to win your affection, within the bounds of relatively normal behavior.
Inspire hope or despair. With a successful Diplomacy check against DC 25, you fill a single target with hope or despair, as if affected by the good hope or crushing despair spells. In the case of despair, the target can negate the effect with a successful Will saving throw (DC 10 + 1/2 your Diplomacy ranks + your Charisma modifier).
Cause confusion. Make a Diplomacy check opposed by your target's Sense Motive check. If you beat you target's check result by 10 or more, you can cause him to become confused for 1 round. You can use this ability as a full-round action.
Changing an NPC's attitude toward someone else is a great use that would probably be alright as-is.Inspire love and devotion though? In short, you're such a good diplomancer that you can make anyone horny for you. Inspire hope or despair are certainly interesting ways to use Diplomacy, but it's essentially at-will use of either spell, which are third level bard or fourth level sor/wiz. Cause confusion is at-will Lesser Confusion, a first level bard spell. It's an opposed skill check, which means they don't automatically save and you can automatically succeed if your check is high enough. Fun stuff.
