[@vancexentan]

How does Imperial Privilege grant Nero Divinity or Eye of the Mind? The answer is it just works because everyone believes it works, Arsene is the greatest thief in the mind of the public so he can steal anything. And there's no Servant that's rendered just completely useless by the sealing of one skill, even if there was than that would mean it's such a powerful skill that it's a gamechanger for it to get stolen, which is the purpose of a Noble Phantasm. A Noble Phantasm is supposed to be powerful. Literally this is Arsene's entire kit, if you take this away from him he has nothing left. Imagine if Excalibur didn't just kill everything immediately or if Kojiro didn't have Tsubame Gaeshi. Sure they're still strong sword people, but that's all they become, they lose the thing that makes them most interesting.

In Arsene's case, he doesn't even have anything that makes him interesting to play aside from being really good at stealing everything. I dunno what to tell you man, Arsene kind of becomes useless in a fight unless he has his Noble Phantasm as it is. If he can't steal other Noble Phantasms and he can't steal skills then what can he steal that's actually meaningful in a fight?