Thanks for these responses. Just a note, my player doesn't want to just halve enchanted item blocks, but all blocks.
This, to me, suggests a possible 'inadvertent house rule' regarding blocks. Because they're pretty much useless at low values (which a value of half peak skill definitely is except against mooks).
Could you explain your table's understanding of what it is that a block accomplishes?
I think his issue with aiming is that when he looks at the books series, Harry misses with his spells quite a bit. What I'm not sure he understands is that, from a mechanical perspective, Harry's control, and thus targeting, isn't all that great, at least at the start. As stated in Our World, he's got Superb Conviction and only good Discipline, and any of his focus items only give +1 control at best.
This, on the other hand,
screams 'inadvertent house rule' regarding what it means, narratively, for an attack to 'hit' mechanically.
Inflicting stress does not mean that the target of the attack took that ball of fire straight to the face. In fact, unless a consequence is inflicted, it doesn't even mean that a single hair on their head will be singed.
Even if they DO take a consequence from an attack, even that doesn't necessarily mean that the attack itself caused any harm, narratively speaking, at least. They could have twisted their ankle while desperately throwing themselves out of the path of the fireball hurtling towards them, or any number of other 'third-party' sources of injury.