Everyone hates the spell earthquake (Unless your the small percentage of Myth wizards out there) so if there are spells that can take or break shields or charms. Why not have a spell to protect them? A sun spell that changes the color of the blade, or shield, or trap, or whatever it is, and they're protected.
The counters to earthquake and enfeeble are stun, mantle, smokescreen, dispel, mana burn... This idea would unbalance things too much. You want to take away Myth's and Storm's only real utility spells without giving anything back.
If they were to do this, they would have to put a "Destroy Blade" that would be it's own blade that removes EVERYTHING without "Protecting your Blades" on it. Which would remove stun shields, etc, bringing back a lot of problems. They would HAVE TO put something in like this because, for one, Earthquake would be useless since it couldn't remove blades or shields anymore(let's face it, they'll be able to be used on shields, just like "Cloak"). Two~ It would help them!!! Thank about it, it would use sixth of your enemies pips, for only 585 damage(WITH COLOSSAL!!!), then it would remove any dispels, weaknesses, etc, that your ENEMY has on.. Think about if this could be used on weaknesses, Efreet could only be HIT OFF!! Which would mess up Balance... This spell would just bring up way too much trouble..