Magic Resistance: D
Emiya’s Magic Resistance is weak; its rank is D. In other words, spells greater than one bar will overwhelm this resistance. The benefit it provides is equivalent to an anti-magical amulet. This level of resistance can be easily overcome by a relatively powerful magus.
Although Emiya was a magus during his life and possesses unusual Projection magic, his affinity with magic is far inferior to that of ancient Heroic Spirits to whom magic and Sorcery were commonplace. The level of Magic Resistance is a result of this.
For Emiya, who possesses low Magic Resistance, it is easy to picture the kind of effects high thaumaturgy and rituals can have on him.
Even spells greater than two bars can be lethal to him. Because of this, Emiya is at a disadvantage against Caster, who has powerful magic at her disposal. Depending on the situation, Emiya may even have to guard against attacks by Masters who are magi.