This is a spell my current maga is working on. It's being developed in reaction to some problems with mundanes, but unlike my Helmet of Skewering, it's in the style of the character I'm actually playing.
Without much further ado, I present:
Lisette's Mystical Transformation of Swords to Fish
This spell has a simple and often humorous result. It turns one sword into a live fish of proportionate size for roughly two minutes. It's both surprising and surprisingly effective, as most people have an adverse reaction to their favorite weapon suddenly becoming a salmon, especially a live one.
It was created by Lisette filia Berard of Bonisagus in order to prevent mundane attacks in the least harmful way possible. As the fish becomes a blade again after a few minutes, it leaves no mundane evidence, either. After all, who would believe it?
Guard: I went to question the girl, sire, but my sword became a fish!
Lord: A fish? Really?
Guard: Yes, sire! I think it was a salmon. It may have been chad.
Lord: You aren't certain?
Guard: No, sire. I didn't taste it, after all.
Lord: Indeed. You had no cooking apparatus with you when your sword was turned into a fish? Perhaps you forgot it in favor of the large quantity of drink you seem to have consumed instead...