I could see the weapon enchantments you're mentioning. There are two promo card incantations out now actually. One of which you give a creature Fire Damage on it's strikes until the end of it's next attack(I think) and the other gives lightning. They're both level 1 spells for their respective schools. An enchantment wouldn't have to be unable to be dispelled if simply dissolving the weapon would take care of it. I mean you could dispel the enchantment and not have to worry about Nullifies but eh I'd just dissolve it.