alvarro wrote:
I am not sure how spells cast on weapons work, if they count as devices or not? Would you get impaired by resisting a weaken cast on a weapon?
No, you should not. Think about it this way: impairment is a consolation prize for risking taking the time during combat to cast a spell which would do nothing if the target successfully saved. If the spell is pre-cast onto a weapon, you aren't taking any additional risk. Given that, I'd still say it's preferable to pre-cast it onto a weapon if you have the time to prepare before combat.
Note that many warlock spells are impairment as well, even though they still do half damage on a save. In general, there are two categories of spells that got impairments - maledictions and warlock spells. They both got access to the new system, although for different reasons. Warlocks got it as part of their buff package.