It is a travesty that the "mundane" spells don't get an affinity potion buff. All the other spell types do get a +3 buff which is significant if used with arcane marksmanship or other synergies.
The damage bonuses from the piercing and slashing capstones are unreliable, and more generally capstones are not relevant for ward-bashing as everyone uses aura+touch attack for that anyhow.
I propose that strength potions give a damage bonus to slashing, impact, and piercing spells. +2 to be consistent with the HtH bonus. I think it makes enough sense that a magical strength potion would add to the force behind these evocations.