I’ve had this quest that says “Go to the south gate to find a Stone Sword with a golden hilt near the wall” — if you always look at the map to see where you are going, this should be pretty easy for you. You should be able to see an extension on the map, but how to get there will not be too obvious as first.
After entering the south gate from Prontera, just go to the north west part of the map where you can clearly see a passage way and an extra chunk of land. To get there, just go behind the carnival tent and the Poring hot air balloon.
You should be able to see the sword immediately. Just click on it to trigger the event — careful though, you will find yourself surrounded by Dark Monsters which I thought were cute vampire-ish girls at first, but as it turns out, they are actually a bunch of dudes wearing stylish underwear.
If you’ve finished finding the sunset painting near the west gate, this would probably be very familiar to you — your ass will eventually be rescued by an NPC named Tammi.
I hope this helped. Happy gaming! 🙂