(IIRC...)
Swashbuckler gets its Int bonus as a damage bonus to light & finessable weapons, but it's not an insight bonus.
Champion of Corellon (Races of the Wild) gets a similar ability, but the Dex bonus is applied. The Shadow Blade feat in Tome of Battle is similar to this, but applies the Dex bonus to weapons of the Shadow Hand school. But again, these aren't insight bonuses.