Do you have the multiplier list for everything? What about the other specials?
I don't, but Gray@Izumo has, so I quote them from
his site, which he allows to everyone.
Item Property: Slayer(*2), Killer(Max:*2)
Chivalry Spell: Enemy of One(*1.5)
Special Move: Crushing Blow(*1.5), Armor Pierce(*1.5), Shadow Strike(*1.25), Talon Strike(*1.2), 1st Hit of Double Strike(*0.9), Whirlwind with Bushido(Max:*2), Force of Nature(*1.65), Self-Invoking of Honor(*1.25), Perfection Bonus(Max:*2), Honorable Execution with Perfection(Max:*2.2), Death Strike(*0.5) etc.
Not all, but most.
Why does the demon slayer part of a Xbow get canceled when you use concussion blow?
Some special effects on Weapons go off before the original damage. For example, Harm and Lightning on weapons go off before the damage of original hit. The slayer effects with this kind of effects are cancelled. The added damage of concussion blow is given to the target also before the original hit, and therefore the slayer is cancelled as well.
The effect of which damage is given after the original hit, e.g., Magic Arrow and Fireball, doesn't cancel slayers.
Why does double slayer work on Dark Father? Is he weak to all elemental slayers? Sure seems like it.
This is a kind of buggy effect, so I can't describe it in public. I can only answer to the latter question, Yes.