Put me in the against camp at the moment. Maybe I'll change my mind if I see them in action but I don't like the flavor or crunch of the cyrstals. If they were a full minute to swap out, I'd like them more, but still it takes the flavor away from the weapon.
Why not just have the Halberd of Golan Duur? This is an ancient weapon made for the hobgoblin champion in honor of his saving the daughter of the Empress. In order to be able to defend the empire against any foe, the halberd can alter its properties to suit its enemies. Concentrating on the weapon for a full round (which does provoke attacks of opportunities), the bearer can apply any of the following properties: flaming, frost, electricity, sonic, ghost touch, or keen.
You could even boil that down to a +2 property called elemental or flexible. You get the same concept but now it actually has some fun to it (my definition of fun, yours may be different).
Why not just have the Halberd of Golan Duur? This is an ancient weapon made for the hobgoblin champion in honor of his saving the daughter of the Empress. In order to be able to defend the empire against any foe, the halberd can alter its properties to suit its enemies. Concentrating on the weapon for a full round (which does provoke attacks of opportunities), the bearer can apply any of the following properties: flaming, frost, electricity, sonic, ghost touch, or keen.
You could even boil that down to a +2 property called elemental or flexible. You get the same concept but now it actually has some fun to it (my definition of fun, yours may be different).