Spin-off from this thread.
If you want the player rather than the character to be creative and to make magic poetic I'd write spell effects as normal sentences and have any skill checks determine whether the spell could be applied to an ambigious (not any) situation.
"Make a sword return to its scabbard" could be a mind afflicting spell making someone stay their hand in a violent situation, or a telekinetic effect making the sword literally return or have a man rush to his lover. This effect could be used to find a path by purposefully separating a sword and it's scabbard and later casting a spell on the sword. Axe wielding warriors and eunuchs would be immune to this spell. The reverse of this spell would be powerful too.
The spell effect is written in natural language.
It is ambiguous enough to apply to at least two situations without being a stretch.
It's specific enough that there aren't more than a handful of obvious applications.
Bonus points if the power level is what you'd expect from an adventuring magic user.
Just the effect is enough, only clarify and expand if you really want to. Here's the start:
"A sword returns to its scabbard."
"A flame burns through the night."
"Bloody tears stain cloth."
"A message is carried on the wind."
"A seed takes root."