What are Spirits made of

[Ertxiem]

Hm. This is nitpicky, but I'm curious as to why you would think psy energy functions like a liquid when given physical form. Why not a gas? Indeed, a gas would make more sense, since spirits are described as "dissipating" when defeated. Gases are the only substances that can dissipate, really.

In fact any fluid (liquids and gases are fluids) can be dispersed in some other fluid (but not necessarily into any fluid). If the amount of one fluid is significantly smaller than the other it appears that the first fluid disappears into the other.

In that sense, the psy energy would be spread all over the place and the people (humans or not) that have psy skills can transform the psy energy to other typels of energy (producing heat or movement) and transform other types of energy into psy energy (creating cold regions or absorbing kinetic energy reducing the impact created).

Regarding spirits, if they can control the psy energy, they may choose to create solid areas in a shape of a weapon. The edge of the weapons being like ice seems reasonable, due to some spirits using cold attacks.
Under this view, some of the spirits may be more like a dense liquid, thus more susceptible to physical attacks and other spirits may be more like a less dense liquid or even a gas, thus less susceptible to physical attacks.

[SmartyPants]

Everything Ertxiem said make sense, but I am a little skeptical spirit weapons being like ice.  If the ghost knight's axes were like ice, then Luca's physical resistance wouldn't work.  I think it more likely that the spirits increase their weapons' density right before they attack.  If the spirit makes the "fluid" weapon dense enought, then it becomes akin to a solid.

[Ertxiem]

If you read my post again you may find that I said that "The edge of the weapons being like ice seems reasonable". So, I wasn't saying that the whole spirit would be like ice, only the edge of the weapon.

[SmartyPants]

I understood what you met.  You were saying the part of the weapon that strikes enemy is like ice.  But if the edge of a weapon is like ice, then physical resistance wouldn't do anything against Rajav and Ghost Knights.

[Ertxiem]

Mmm... I wasn't thinking about spirits fighting spirits... I'll have to think about it...

[Chocobo_Fan]

I think what Ert means is that the edge is merely solidified. If we accept the hypothesis that psy energy (and by extension, spirit bodies) acts like a liquid or gas, then spirits would merely "freeze" the psy energy representing their weapons, causing the energy to solidify and allowing it to interact with physical objects. This would be functionally identical to an ordinary physical attack, not a cold-elemental attack, since the important part is something solid smacking into you, not the freezing temperature. Thus, the spirits' physical resistance would still work.

Edit: I just realized there is support for this -- ghost knights' axes seem to gleam and change somewhat right before they attack. This could represent the solidification.

[Steelfist]

His spear could be non-corporeal, but the space that it occupies becomes very, very cold (Thanks to spiritual cyro affinity), producing a physical effect.

The weapon harms spirits, as it is technically a psy cyro attack, but it is wielded at a physical weapon and causes physical damage through cold or ice. Perhaps the cold intensifies, and the gleam is moisture condensing into ice at the moment of the attack. Or perhaps it's always a spectral spear that exists in the same place as the created blade of ice; a physical and psy weapon in the same place.

[SmartyPants]

Maybe the liquid that spirits are made of have a higher freezing point than water.  That means that spirit wouldn't have to make itself very cold to be solid.  If the spirit weapon isn't below below 0 °C, then it won't do cyro damage.

[Steelfist]

The cyro affinity makes it likely that their attacks are cyro based.

[Chocobo_Fan]

Alternatively, the spirits could simply be pressurizing their energy (or magically solidifying it) instead of freezing it. That would produce the same effect without the cold vs. physical conundrum.

Also, I think spirits only have a cold affinity because "death is cold" is a common trope in media. It seems like affinities only affect purely energy-based powers like the Blasts, anyway.

[Steelfist]

But spirits are energy based themselves; they'll probably be affected by their affinity.

[Chocobo_Fan]

Which would be in line with Greater Ghosts having cold resistance.

[SmartyPants]

The cyro affinity makes it likely that their attacks are cyro based.

If the attacks had cyro affinity, then they would do cold damage.  If they spirits' melee attacks were considered "cyro", then Rajav's spear throw would harm Greater Ghosts.  Spirits only seem to be harmed if you attack them at a molecular level or with mental attacks.  If the spirits' melee weapons were extremely cold then they would do damage at a molecular level.

[aziz]

It could be that rajav's spear is just psy power and when it touches the enemy's brain thinks it is being hurt.so the spear could be just psy power in the shape of a spear connected to rajav.

[bugfartboy]

Nice theory. My question is: Wouldn't that make it mental damage?