I have been moved by your great argument. In-fact, the scales have fallen from my eyes, and I realized that since all magecraft is 4D, and magecraft can be fueled by life energy, ergo
every single human in Type Moon has 4-D bodily fluids and is thus immune to blood manipulation of infinite reach and power. And they are all able to fight with their bare limbs, which is the most primordial combat method as provided above, so they have 4-D martial arts too, clearly.
No it isn't. Luffy doesn't suddenly gain access to 4-D abilities because he is fighting a servant.
He doesn't get access to any 4-D abilities, you are right. Having Mystery isn't an ability.
Anyhow, I can't believe we're now unironically arguing about whether all servants are immune to anything below tier 2 because of muh Mystery. I am genuinely mystified about how anybody could read any of the novels, or play the games, and get that idea.
Servants are vulnerable to anything that is old, or supernatural. That's it.
Mystery is a 4-D concept in Nasuverse. A servant's invulnerability is dependent on such a concept. If your shit doesn't have Mystery, it can not harm Servants. Thus the 4-D Invulnerability argument here.
Mystery and their invulnerability were already accepted as 4-D in a CRT. You are simply choosing to ignore what is accepted on the wiki.
I mean, for one, imma need a quote on that? Preferably a quote for the source in the story, but you can just quote where it was accepted that Mystery itself is 4D.
Secondly, that's absolutely covered by verse equalization, for the same reason a character gains a "4-D soul" when fighting a Servant/Magus/Phantasmal that targets the soul, because it is fundamental for their interactions. Artoria and Luffy cannot exist in the same world without either Luffy not gaining Mystery due to how Type Moon works, or Artoria dying for the lack of Mystery, and we both know which one would be done for a vsbattle.