Why not have a method of immunizing weapons via WM magic?

Make it a WM only thing, or guild only ie Clerics do thiers.. Moonies do thiers etc or have it a join thing where a WM,MM Cl or whatever needs to be with the forger.. add some magic to the forging process so that when flame, frost, electricity is added it is kept in check by the "aether coating".

Actually scratch that. Warmage magic and Barbarian doing barbarian stuff at the same time is just bad.

Anywho.. something like that. That way.. once you flame your weapon and the duration ends, you can frost it, or whatever.