When using Huntsman and trying to get swift slaying on mace and sword, spent around 150+ dust before swapping to Footknight and got it in around 10. Might be insanely unlucky. But better to be safe than sorry.
I’ve just ran through 70 dust trying to get Swift Slaying on a Coghammer using Outcast Engineer, specifically the cog wheel button under the ‘Equipment’ tab.
When I swapped to Ironbreaker and used the actual ‘Crafting’ tab, I got it in 3 rolls.
Thank you for reporting this, I thought I was going insane.