After doing some digging, and making various theories, I found a way to connect the cursed blades/El Patron to Davy Jones.
1) Cursed Blades can be found on Raven's Cove AND Isla Tormenta where Davy's crew is.
2) Many of the cursed blades are used by Davy's crew in the movies and in character concept art of Davy's crew.
3) Curse of Doom is very much like the Black Spot.
So by seeing all this I concluded something, it seems pretty wild to me but, seems possible that the game developers may add this:
El Patron and his crew stole a huge cache of cursed weapons from Davy Jones, being mortal, it cursed them with the Black Spot, known to them as the Evil Curse of Doom as they did not know the stories behind the Black Spot. As they were sailing away the Kraken came after them, forcing them to land on Raven's Cove and never leave, because if they did the Kraken would attack. Then El Patron began to wield the curse (which is how he was able to seal Foulberto in Cave of Lost Souls). And now since the player (at LV.30) got the curse, the Kraken is after him/her too. And perhaps you have to go through a hole quest which leads to battling the Kraken. And I have a theory on how Jolly is involved in this. In order to use sailors who died at sea, Jolly had to make a deal with Jones, which was to bring back the lost weapons. (Or Jolly just wanted them for his own personal use) Well, that's my theory, I know it sounds a little bit odd, but I'd love to play thru a quest like this if it was real.