It is exotic, but Eagle Claw from Sandstorm is 18-20.
And if you start to consider Feycraft stuff (which makes medium count as light I think), then your list will expand quite a bit more I believe.
Thanks for the input.
I looked at the feycraft template, but the 1H weapon is only treated as light for the weapon finesse feat. I need it as light so I can wield to identical weapons and so that my
shield of blades (PHB2 alternative swashbuckler) works.
It was however nice to see a way to "finesse" any 1H weapon. And a way to give the weapon finesse feat for "free" (as in feat wise, not money wise) with light weapons.
I fear that kukri and the Gehenna lancet is the only light 18-20 weapons that doesn't cost a feat, 1 lvl dip or an arm.