I have a bit of a bias against fantasy weapons. Real melee weapons were designed and refined over centuries of combat and warfare. They are very good at what they are used for, within the limits of metallurgy and crafting capabilities of their period. A trade-off like the longsword, where you get a bonus against some armor types but a penalty against others, reflects design optimized for a certain type of combat, and is perfectly reasonable. But when you give a bonus against all armor types, you have to ask how that is possible. We tend to treat katanas as superior to broadswords but it's not really that the shape of the katana is so superior, the main advantage of the katana is that the metallurgy is better. It makes more sense to stat the weapons a bit more similarly, but then specify that katanas are normally made from high steel II, with the inherent bonus, and price them accordingly. That will scale better once you get to even better materials (e.g. if you make your katana out of mithril it should raise the bonus from +10 to +30 rather than adding an additional +30 on top of the bonuses it already gets for the high steel it's not made of).
So, why is a long kynac better? It could be that its makers have figured out a way to improve the shape of the weapon in a way that vastly improves its use, but then there's no reason why every culture exposed to this amazing development wouldn't have copied it, and it assumes that there is something universally inferior about the design of a rapier, which seems questionable. Or, there is something vastly improved about the metallurgy and crafting techniques that go into it, in which case it should be treated as being of superior materials (e.g. enchanted steel II or white alloy) which will give it a price appropriate for its value, a reason why other cultures can't copy it, and more realistic scaling if you try to use other materials to make one.