Edge of the Chair Leg
MuTe 40
R:V, D:S, T:G
This spell targets a group of upto 100 bladed weapons and rounds the edges of their blade to make them blunt. They now do crushing damage instead of piercing damage.
Base 3, +2 voice, +2 sun, +2 group, +1 size, +2 metal
The perfect weapon for the magus going into battle.
you need to check on what makes a weapon "do" damage.
A blunt sword does not do the same damage as a sharp sword but as "crushing" instead of "slashing" damage.
The process was normal in ME, and was called "rebating", and was used to prepare practice weapons.
To be effective like a mace, you need a heavier weapon and one which focuses the impact (typically to a more or less pointed spike or flange)
The spell proably reduces swords to (say) "half damage"
But that is half-damage against your grogs, the enemy's magical swords will no-longer hurt you, as you cast it with little penetration and they bounce off your parma.
You are going to have people huddled in the corner muttering 'pink dot' to themselves over and over again.
PINK DOT CHEAP OUT!
Kinda like that?
Oddly enough that was exactly what I was thinking of.
Didn't it use to be called "Edge Of The Spoon" ? 
I have just searched "Edge of the Spoon", and stand corrected. Grogs will take less damage, but the concencus is that the magus would still be hit by the blunt sword.