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Expanding on this - this ''Void'' is not the the ''Void'' that sometimes is associated with Hollow/Imaginary Numbers/''possible but not in the physical plane'', but the Void as in the Fifth Element, as in Emptiness that is used to describe the Root/Akashic Records.
A Servant in spirit form was incapable of taking any offensive or defensive measures. ... |
So no spiritual attacks. If they become invulnerable to other Servants in Spirit Form this would be a great defensive measure, and we would've seen a bunch of cowardly Servants abusing this.
This may be interpreted incorrectly, though. Servants in their Spirit Bodies could affect physical objects as far as original FSN, so to say INCAPABLE of offensive measures is incorrect if taken literally. If interpreted in a context of a servant vs servant fight, it would be acceptable, though. The fact defensive measures against physical interference are useless (unless the ''physical interference'' came from Servants or spiritual rank beings) should be noted, and it's awkward to question if a Master/Mage possesses the means of attacking a spirit body, given Reinforcement, for example, is defined as the basis of any Magecraft, and the ability to shot magical energy as it is, without real manipulation exists.
when the servant is in a spiritual state, other servants cannot harm this servant even though the servants have spiritual attack abilities
Not really. Servants repeatedly demonstrated the ability to strike ghosts in their physical form, and ghosts have little to non-existant ability to interact with the physical world and vice-versa without possessing a physical body.
Servants are, in the end, magical energy even if said energy is given physicality as in the Material Body. Spiritua Beings cannot go through magical energy ''laced/imbued'' things, a.k.a. the Material Body of Servants can affect Spiritual Beings as an intrinsic quality - even if as Material Bodies, they have ''Spiritual Rank''. Servants as Spiritual Bodies are still Spiritual Beings, and the effect follows. Ghosts are literally one of the lowest classes of Spiritual Beings, and any type of magical energy could do short work of it.
If by ''Spiritual Attacks'' you mean attacks that can affect Spiritual Bodies and Beings, everything a Servant does is such. It's the ''right'' of a Servant to do so, to even through physical interference, affect spiritual bodies.
And I would like to ask when/where such a case where a Servant as Material Body couldn't harm another Servant because he was as Spiritual Body took place.