Everyone knows slayers are great, but I always wondered: are they better than something like a +25 vanq with all of its bonuses being applied? I tested a +15 Vanq Maul and a plain Silver Maul against a bunch of liches, and found: +15 Vanq: 19.46 damage per hit plain Silver: 28.56 damage per hit So the answer is YES, by a significant margin. Even if you're using an Agapite Runic weapon, you'd be slightly better off with a plain slayer with no other modifiers.
One of my favorite comedians has a joke about how if you dropped a bunch of beavers on the roof of the Empire State Building, they'd start looking for trees to build a dam.
2x Base Damage will nearly always be better than +9 (or even +13), unless we're talking daggers or something.