Most people visit the Fire Sea area because it's where you do the Hellfire Knight quests.
The Hellfire Knight can acquire a 4-star greatsword from a nearby field.
You can get a 4-star greatsword with simple controls, so if you have to go to the Fire Sea, don't forget to grab it!
The name of the 4-star greatsword you acquire is 'Twilight Ardor'.
Teleport to the Fire Sea Small Beacon
Move straight along the road, and if you see an updraft on the left, jump and ride the updraft.
When the updraft ends, climb over the wall
If you go over the big wall in front of you again
You can acquire the 4-star greatsword Twilight Ardor! The coordinates are -1497,2071,194.