[Skarg]

I think of it like this: A wizard who gets Aid ST has magic spell energy for 10 seconds, that makes them stronger, able to use the energy for spells, and perhaps able to stay conscious in spite of wounds. If they cast a spell with Aid ST, the spell uses the energy of the spell rather than their own strength.

I am not at all able to imagine it as layering on physical muscle that would get neatly reduced by a wound such that after being hacked up, they're pristine after the spell wears off.