I’m thinking later into the story Morden is going to be corrupted by the Sea Curse. I feel like at some point he’d by accidentally use the curse on someone important in the future of the story and try to reverse it. Then either it doesn’t work and he dives into madness or it works similarly to necromancy, the body is brought back but not the soul. My reasoning for thinking this is because of the Death Curse and the perk of having a Sea Curse. Sea Curses grant the user of having immortality so you can’t die to age and you’ll stay well. Since Death and Immortality are quite the two opposite things I feel like that’ll lead to a weird occurrence later on. It’s just an idea for now but I think Vetex particularly added this fact maybe because of the Death Curse and having Morden a main character makes sense.
Sea Curse Mental Corruption
Since the sea curses have so much power I would think it’d have to drive some ones mental down the road. I personally feel that the less powerful curses like cloud or maybe growth doesn’t make the person unhinged, but the more powerful the curse is the more likely it is to make them unhinged. Since like Devil Fruits from one piece have a draw back for example, they can’t go into water at all and once the user dies the power of the fruit they had gets transferred to a near fruit. Yet sea curses have a similar type of idea where when the person dies they sea curse flies away unless they use a Devourer sword. There isn’t any drawback of having a sea curse unless having immortality counts as one.