If Tifa and Aerith fought...

[Ryushikaze]

Wrong, my good sir. CANON agrees with Wikipedia.

Prove it.

And still, you refuse to deny my original statement, about humans being the Cetra who stopped listening to the planet. Before you scoff at Wikipedia, please porvide some evidence as to why it's wrong.

Because it IS wrong. The cetra are not unique in their ability to listen to the planet.

Bugenhagen studied the Planet for years in order to be able to hear the Planet. By the way, Holy only called one person in the whole game, and that was Aerith. And by a startling coincidence, Aerith is the only Cetra left. Why didn't it call to Bugenhagen?

He wasn't wearing it in his hair.

Suddenly, Cloud saw Sephiroth kill two people with his Masamune. We watch a movie of Sephiroth walking away with flames all over the place. Cloud then proceeds to the Mako Reactor. He saw Tifa's father's dead.
Tifa: Papa... Sephiroth!? Sephiroth did this to you, didn't he!?
Sephiroth... SOLDIER... Mako Reactors... Shinra... Everything! I hate
them all!
Tifa took the Masamune and ran. As Cloud head to the reactor section...
Sephiroth: Mother, I'm here to see you. Please, open this door.
Tifa: How could you do that to papa and all the townspeople?
Tifa attempted to slash Sephiroth with the Masamune but Sephiroth took the sword from her and slashed her. Then Sephiroth went inside the room with Jenova. Cloud helped the wounded Tifa.

Masamune is a sword. Only Sephiroth could wield it meant he was the only one strong enough to actually use it effectively. Anyone could pick it up, but is would be too big to be useful. Just like anybody could hold the White Materia, but Aerith was the only one who could pray to the Planet and unlock Holy. Note that Sephiroth, unarmed, ambushed by Tifa, took the Masamune from Tifa without blinking. Furthermore, that whole sequence is based on Cloud's memories that Zack actually witnessed. It may not even be 100% accurate.

Doesn't matter. LO is a third person omniscient. It is canon.
I'd also like to see your source on 'Only Sephiroth can wield it.' This should be good. Especially since with a name like Masamune, it was almost certainly forged by the wutai, and not for Sephiroth.
By the way, how is any of this relevant to the point- and not my analogy- of battle equipability relevant to plot usability?

The following evidence comes from the site http://au.faqs.ign.com/articles/698/698416p1.html. It was taken from a translation of the Ultimania guide. My thanks to you, Ryu Kaze.

**The White Materia: Holy** (005.3B)
The only means of opposing Meteor, the Ultimate White Magic was passed down amongst the Ancients. It is said that when an Ancient learns of Holy in the Forgotten Capital, prays at the water altar and their mind then links to the Planet, Holy is thereby put into operation. Passed down through the Ancients' generations, the White Materia came to Aerith from her mother, Ifalna, and she kept it hidden in a ribbon in her hair.

How exactly Holy applies its power once invoked and in operation is not
definite. It is simply known that "all that is bad for the Planet will
disappear."

(Accompanying screenshot caption)
As evidence of the Planet accepting Aerith's prayer, the White Materia laying on the water bed shines a pale green color. However, Holy's movement was being held back by the wicked will of Sephiroth, who had called Meteor.
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[Analysis: This section confirms what many who played the game believed: that Aerith knew nothing of Holy until she got to the City of the Ancients -- to which she felt herself being drawn -- and learned of it there, the same way that Bugenhagen later would.]
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Which doesn't actually prove "Only the Cetra may use said Overide/Abort", and completely fails to address the argument that if it is, they are the stupidest people in existence.
I also have to disagree with Ryu here. It does NOT actually confirm his conclusion. It actually does not mention her knowledge of Holy before being at the city. Now, it does not disprove that she was unaware before arrival, but it is not conclusive.
At best, it supports the concept that Aerith didn't know the will of the planet until she arrived at the altar.

Sephiroth, and only Sephiroth, could use Black Materia because he spent years in the Lifestream, and so gained all the knowledge of the Ancients. He would be able to use Holy as well, and Aerith could use Meteor, but why would they? There's your evidence. And for the record, it would not make Cetra stupid, but the Planet, since it created the White and Black Materia.

Actually, he learned how to use the black materia by reading the instructions inside the temple of the ancients. Though even if your assertion here is true (which actually contains no evidence, despite you saying it does), it bears out MY argument, that it is the knowledge of the use, and nothing else, that allows one to use Materia.
And the Planet formed an intricate hewn temple temple staffed by the lingering conciousnesses of dead Cetra devoted to staffing the place. Riiiight. Now pull the other one. It's got bells on.

The chance of Deathblow working may be low, but if she uses it many times, which she can thanks to GG, the chance of it working just once rises exponentially.

And it only needs to be used once on Tifa's end for her to win.
Tifa wins init, uses deathblow, Aerith doesn't even get a chance to GG. That's without the sneak attack being put into play.

Wrong again. Aerith knew nothing of Holy until she got to City of the Ancients, she only knew what the Planet was telling her.

And? Even if true, how does this go contrary to the concept of "Do not put my friends in unnecessary danger"?

Except for White and Black Materia. They are very different to normal Materia. Do some research.

Show me some evidence, instead. You claim Meteor and Holy require special activation. Prove it. We've got a secondary source and Aerith, who you, by the way, are now indirectly claiming didn't know what she was talking about when she sent the message to Cloud.

Because Aerith knew nothing of Holy until she got to City of the Ancients, she said that because the White Materia, when calling to her, told her that. Aerith may not be infallible, but the Planet is.

But she wasn't at the city of the ancients when she sent the message. So she's not been told that information yet, by your argument.