Well I have never removed a Wa handle. But I have removed the heads off lots of golf clubs which are epoxied in place.
Any handle that is epoxied in place, you might have luck with an electric heat gun, just waving the heat gun on the choil area on both sides.
You should wrap the ferrule with aluminum foil if you plan on trying to save the old handle.
The heat generated by the electric gun is hot enough to break the epoxy bond, but not hot enough to ruin the temper on the steel.
As far as that rubbery sealant TAZ mentions, probably does a great job of preventing moisture from getting inside the handle, but lousy odds of removing the handle.
I have a golf club head remover that works like a charm.
I wonder if I could jury rig it to pull knife handles?
The shaft clamping device can be removed, then I could put tape on the part of the blade inside the clamping mechanism.