I think if it would be like you suggest, then the description on Skull grasp would say "increases whirlwind damage by 440%" but instead it says "increases whirlwind damage by 440% weapon damage", which leads me to my conclusion.
Anyway: even if it is like I said, it should still be worth more than a soj dmg wise.
If you compare 3*349% + 440$ = 1460% to 3x340% = 1020% you get a flat 43.1% increase on all whirlwind damage dealt. And this is on a secondary slot. I doubt that the elite dmg and ele dmg (which use up a primary each) on a soj make up for this.
Only thing I could imagine to be worth it: take RoRG and use Hexing Pants instead of the Wastes Legs. Could be worth it if you need the ressource cost reduction and utilize other dmg sources than WW aswell.
From my understanding the set + skull grasp should work like:
340%*3 + 440% = 1460%
Since skull grasp states to increase whirlwind by 440% weapon damage and not by 440% and they said it would be addditive to the setbonus.
Since you need Skull Grasp + Unity in solo play, there sadly is no possibility to use hexing pants and as BartekSWT said, you will also need a pride of cassius.
I should test if it is possible to WW infinitely with BK set + weapon master. If so and if + WW damage from skull grasp and Wastes set affects the WW from BK set, I think this should be the best option for this build.
Anyway: even if it is like I said, it should still be worth more than a soj dmg wise.
If you compare 3*349% + 440$ = 1460% to 3x340% = 1020% you get a flat 43.1% increase on all whirlwind damage dealt. And this is on a secondary slot. I doubt that the elite dmg and ele dmg (which use up a primary each) on a soj make up for this.
Only thing I could imagine to be worth it: take RoRG and use Hexing Pants instead of the Wastes Legs. Could be worth it if you need the ressource cost reduction and utilize other dmg sources than WW aswell.
340%*3 + 440% = 1460%
Since skull grasp states to increase whirlwind by 440% weapon damage and not by 440% and they said it would be addditive to the setbonus.
Since you need Skull Grasp + Unity in solo play, there sadly is no possibility to use hexing pants and as BartekSWT said, you will also need a pride of cassius.
I should test if it is possible to WW infinitely with BK set + weapon master. If so and if + WW damage from skull grasp and Wastes set affects the WW from BK set, I think this should be the best option for this build.