I have been looking into some oddities surrounding the two taskmasters from the Grave Matters event (Boreanaz the Shrouded and Stathem the Embalmer) with the help of Multigun.
We have made the discovery that, at some point, all normal T4 taskmasters were given the same crafting speed bonus as the purge-only taskmasters, meaning there is zero difference between them now.
Formerly, T4s used Craft Speed 4, while purge taskmasters got Craft Speed 5.
However, the Grave Matters taskmasters were not given Craft Speed 5, but rather the old Craft Speed 4.
This means that while they are better than T3 taskmasters, they are worse than every other named taskmaster in the game - at least when used on a Wheel of Pain.
The bonuses applied to gear crafted in the Torturer’s Worktable is still equal between all T4s, so if you want to use the Grave Matters taskmasters because of their unique appearance, this is where you should put them.
Possibly Funcom could fix them and give them the same bonus as regular taskmasters, but since it seems like we were never meant to clobber these guys in the first place, I doubt Funcom will bother and prefer to keep them uniquely bad.