I'm not an active Thorn user - I tend to favor rifles more - but I've used mine and faced down enough of them used by others to know that any of the nerfs you recommend would kill its PVP viability. As it stands, Thorn's residual damage is barely on-level with the Incendiary Knife, and it doesn't stack with itself or with other afterburn effects. It's pretty much as balanced as it's going to get. Thorn's prevalence isn't due to any one real magic bullet of a situation, but more due to the combination of Auto Rifle nerfing (resulting in many players who primarily mained Atheon's End, Hard Light, and Suros Regime leaving it en masse), paired with players just not liking the other main weapon types (Pulse Rifles and Scout Rifles are dramatically under-used, even though Bad Juju and Red Death are amazing by all accounts). Thorn is one of the only Exotics that pretty much any player can get that will actually see constant use because it's that damned good at what it does. There's no RNGesus involved with Thorn - it's all your own skill and strength. There's better Hand Cannons, even in the Legendary tier, but none that are anywhere near as easy-to-get, ubiquitous, or effective as Thorn is for how good an investment it is. The solution isn't to nerf Thorn, it's to carefully adjust the other weapons for improved usability. Rather an a blanket buff to Auto Rifles, a more measured, analytical approach is needed, with each weapon receiving detailed analysis.