Bungie said themselves that Yor and Ward were old friends. They each had their own ghost as Yor speaks to both of them in the grimoire and it's all but confirmed that Thorn was The First Curse, Last Word's sister weapon. It was a good theory back in year one but it's been disproven.

No where has it even been close to confirmed that the first curse was the thorn

Just look at the gun. It's Thorn. Same underlying shape, green glow, and if you notice the most important thing about it: the marking on the cylinder. It's a ROSE. The markings left by Yor in places like moon are of a fully blossomed rose, but look at the gun. The markings are clearly a rose. And as we know the man who was Yor called his gun Rose or thought of it as one, it was almost certainly The First Curse. It's for these reasons and more, specifically it's relationship to the Last Word, that it's all but confirmed as I said. Bungie hasn't come out and said it but anybody with half a brain can infer that The First Curse was the Rose that became Thorn. You really should change your name.

Your theory is so bad bud. No one except yourself believes that crap in the Destiny community so I'll just keep my name.