A Black Ship to Transport Slaves...
I wonder if Oda is doing his Version of Black Pearl & Jack Sparrow Story
"The Black Pearl's Backstory begins as The Wicked Wench, a merchant vessel captained by Jack Sparrow for The East India Trading Company. When Sparrow frees slaves, his Employer, Cutler Beckett, brands him a Pirate & sinks his Ship. Jack then makes a Deal with Davy Jones to raise it, which was blackened by Fire & thus renamed Black Pearl. The Deal was that Sparrow would remain as Captain for few Years & then He will have to serve on Flying Dutchmen for 100 Years"
This sounds now like clearly the whole Inspiration for Man With Burn Scar, and our only Clue about his Identity is that it's Someone who once worked with WG but ended up Freeing Slaves, which made WG call him a Pirate & his entire Story Changed,
I'm now more convinced that Man With Burn Scar is Vander Decken (or Someone who Inherited his Powers), Captain of Flying Dutchmen,
I would even go as far as say that Will of D. = Will of Vander Decken,