Inquiry
Why is the Masamune able to hurt Magus's magical defense?
Theories
Reflexive Power
Andrelvis, razor's edge, V Translanka
The Masamune is said to depend on the user, not its inherent strength as a sword. It also has a spiritually reflexive nature, evident in its corruption of users in Chrono Cross and its enhancement at Cyrus's grave. When Frog battled Magus, his spirit and many feelings sufficiently fortified it to do extra damage, as he was very motivated. The same mindset allowed Frog to split the Magic Cave with the empowered blade. Frog doesn't hate Lavos and other monsters; he rationally knows that Lavos will destroy the world and must be destroyed before he does so, but there is no personal hatred. Whereas, with Magus there is. Magus killed Frog's best friend. So, there's a huge emotional difference between fighting the two...And the Masamune is based on people's emotions and feelings, not their convictions. As dream beings, Masa and Mune are enriched by the potent desire and will of their wielder.
Magus: W.. what have you done to the Masamune...?
~
Masa: Quite. I guess it means that a Hero's power comes from within.
Mune: Mucha metaphysical, man.
Masa: Like, MIND over matter, Mune!
Frog: My... mind?
Magus seems to be quite shocked that the Masamune is hurting him so. The Masamune didn't seem to help Cyrus and Glenn 10 years earlier when Cyrus was killed. This implies that the Masamune was powered by Frog's will, otherwise it would have worked when wielded by Cyrus. This could be an example of the Dreamstone being utilized in a way not Lavos-related, since it was Frog's dream to defeat Magus and thus avenge Cyrus.
The Hero's Medal (and later, the Shield and Prop Sword in Chrono Cross) also seem to grant psychosomatic powers (unless Cyrus actually imbues the wearer with spiritual fortitude). This means that in simply wearing and wielding these weapons, the user is much more confident and sober in battle.
This theory fails somewhat to take into account the legend surrounding the sword (that only it can defeat Magus), but given the blade's reflexive nature as evidenced in Chrono Cross, this may only be circumstancial.
Dreamstone / Magic Drain
V Translanka
Given Dreamstone's natural ability to conduct Lavos, and Magus's ability to up his magic defense in that battle, perhaps Magus was drawing on Lavos's emanations (who was near due to the summon ritual) to raise his defense, an effect diminished by the Masamune.
An adjunct of this theory proposes that the Masamune, due to its Dreamstone form, can naturally diminish all types of magic energy. This is evidenced in the Masamune II's description, "inflicts 200% damage to all magic enemies." Curiously enough, the sword doesn't actually do this in-game. It also should have a huge effect on Queen Zeal and Lavos, but nothing of the sort is observed.
Magus is obviously not made of Dreamstone, however, so this may be somewhat of a stretch. A third aspect of this theory suggests that Magus's amulet, given to him by Schala, is in fact made of Dreamstone, and this is the tool by which his power is drained.
Masa & Mune
SilentMartyr
The best theory I can throw together is that Masa and Mune know that Magus is Janus, and they want him to not fight Lavos, knowing completely that he would get crushed if he fought Lavos by himself. But that would also assume that they know that he wouldn't get killed in the spar and that eventually he would team up with the right people to fight Lavos. Remeber that thier purpose is basically, to destroy Lavos.
Misconceptions
The Masamune doesn't simply do
~
Inquiry
Why does the Masamune absorb energy from the Mammon Machine?
Theories
Dreamstone Charge
razor's edge, V Translanka
Think of it like this: You take two car batteries, one fully charged and one much less charged. You hook them up to each other and the fully charged one will, over time, lose power to the less charged one, until they both contain the same amount of energy. I think this is a great comparison, since both the Masamune and the Mammon Machine are made of Dreamstone. It's a simple case of equilibrium. Magus is obviously not made of Dreamstone, hence, the Masamune drains his energy for a completely different reason.
~
Inquiry
How did the Masamune become corrupted after Chrono Trigger?
Theories
Knightly Requirement
Faulce, ZeaLitY
Masa and Mune state that until 1020 A.D., they were asleep within the sword. In addition to this, they state at the Denadoro Mts. that only the strong of will can wield the blade. Perhaps, due to their sleeping, people with inferior moral fortitude and strength (contrast to Cyrus or Frog) used the sword, the result being its corruption. Frog had the necessary mettle to use the sword to slay Magus with soberness and purpose, while Radius and the others perhaps were overcome with ambition and could not restrain their desires to use the sword for selfish purposes. This does not take into account the apparent power of the evil Masamune to outwardly corrupt the wielder, however.
Reflexive Sleep
This draws on the Reflexive Power theory outlined at [[Masamune (Reaction to Magus)]]. Masa and Mune state that until 1020 A.D., they were asleep within the sword; the battle with Dario eventually woke them up. Now, considering that the Masamune is capable of expressing the will of its bearer and also absorbing Lavos energy (and perhaps other types by extension), perhaps the Masamune was stolen during the Fall of Guardia and used to commit horrible deeds. This imbued it with a negative energy that remained and also influenced the wielders of the blade from that point on. After all, the Masamune is seen in its original form stained with blood in 1005 A.D. in the PSX cutscene, and is grabbed by the man who slayed the last protector of Guardia. Another idea is that Frog fell to a negative fate after 600 A.D., and that the negative sentiments were etched into the sword in this manner.
Energy Block
Masa and Mune state that until 1020 A.D., they were asleep within the sword. Also, Dreamstone conducts the energy of Lavos. Perhaps while the Masamune existed, Masa and Mune consciously protected it from being negatively influenced by Lavos's energy (note that Lavos energy doesn't necessarily have any outwardly negative consequences). After Lavos was defeated, they went to sleep, feeling their job was done. However, they did not know about the Time Devourer, whose emanations were able to corrupt the blade. However, this theory requires that the Time Devourer still produced emanations comparable to Lavos's energy, and that these emanations could cross the boundary from the Darkness Beyond Time to the outside world.
