Unfortunately I am set up with a swordsman and can't currently use this elite weapon. I would consider a trade for the equivalent weapon in a Katana or Broadsword (Flame or Frost) ONLY. Trade ONLY
I don't know what the drop rate is exactly, but I just assumed it was about comparable to the elf slayers, but only on a scroll type that will get run a lot less often, and can't be iron manned (yet), so there will be more of a split for these slayer types. I would actually prefer the trade for a sword, so I did set the s/b high! If I don't find a sword I may determine at that time if I have the other weapons on hand to make it worth converting to fencing. But you know....if you HAVE to have it, 5m will buy it!
100% chance of a flame bane and a frost bane slayer wep inside of the end chest of the Krampus or White Witch, should you complete it. There is the random chance to get a slayer wep like this from a mob along the way as well. This info came from @Chris