Boss and total damage stacks in KMS.

Was this a recent change or has it always been like this?
I always thought daggers and kataras were separate and not combined, ex: 30% boss on dagger means 30% more damage on dagger hits only.

Daggers and blades are combined now. the damage is stabilized, so all hits are equal.
if your weapons have the following potential stats, you will have 180% boss damage:
Dagger: 30% Boss Damage*3
Blade: 30% Boss Damage*3

same goes for total damage.