I completed my raven's cove story quest yesterday, got the quest to defeat el patron, and open his chest. I selected my cursed blade, then after dancing around on his ship with me friend, I went in to the mines to kill the 4 ghosts standing in a straight line.
After killing around 80 ghosts, I got nothing.
Today, I went to tormenta to kill the 4 guys in the treasure room for about an hour, then went to thrall room for about half an hour, and forget about famed and legendary cursed blades, yesterday and today combined, I haven't even found a rare cursed blade yet.
