Since there seems to be some debate, let's make it clear that if you have a weapon with fire and ice or any other two conflicting types of magic that both can't be active at the same time. If they are the extra damage will be nullified because ice and fire can't occupy the same space. This is proven by Wall of Fire, and other spell types such as Darkness, sorry to add another rule to the bunch. But since it seems that some want to try and convince me otherwise, I am calling it as such.