@Munchmill14, that's never actually said in the story though. It's never said what kind of special properties the sword has at all, in the game. Remember that the game doesn't follow lore 100%.
@TUSF Oh but it was a thought that could be a possibility. I hope all this hype about this being the strongest sword for no reason just because the high stats. I know for a fact this sword has a special ability just like the Demonic Guam sword.
@anon I wasn't referring to the duel in the Fairy Dance arc. There was supposed to be a duel between them after he obtained Excaliber, but I can't find the part which mentions it.
@Munchmill In the game's mythology, it's a "sword that cuts all trees and steel". And the series is only loosely based on the myths, so there's no guarantee that Excaliber has the same effects as in the original legend.
And what did Guam do to be called demonic? :P
This is a Q&A topic, not a speculation topic. If the speculations continue, I will lock down the topic.
First off...
Besides, it has been stated in the forum descriptions that the S,R,&G Board is the board only for such "speculation, rumor, and gossip".
Gsi is serious about "speculations" popping up where they shouldn't be (as with a certain dispute about a tattoo that resembled the emblem of a certain killing guild), because this is a post in the question and answers, where one asking a question would take any reasonable answer that would make a certain item OP.
On a second note, since that the Mother's Rosario arc is a considerable time after the events of Calibur, Asuna was aware of Kirito's skills, and Reki would have stated (in Asuna's POV) that Kirito would be bisecting weapons left and right. Most of us who have read the Light Novel noticed how precise Reki has written SAO—he leaves nothing out.
That being said, Excaliber may as well not have a hidden ability. No one will know until Kirito uses the said sword in battle, and we get a glimpse of his thoughts through his POV.
it is said to be the strongest weapon because it can severe the world tree from that current realm, and because it stopped the world tree's roots from growing, it is likely an ice sword. Kirito hasn't been seen using it so we don't know if it can cut through metal or steel but in the hands of Oberon, Kirito easily reflected the sword because Sugou cheated to get his title and lvl
That description is only lore-based, as far as it is described in all SAO media. And as Gsimenas said...
Gsimenas said:
...the series is only loosely based on the myths, so there's no guarantee that Excaliber has the same effects as in the original legend.
On a side note, Kirito has used it, but only in a secondary appearance. That was when he went "you shall not pass" on that clearer guild so the Sleeping Knights could get a rematch with the Four-Armed Giant. No description on Excaliber's capabilities was noted, and had there been such an effect, the next day's news would have reflected it (just as Kirito introduced his Dual Skills ability).
Also, "cutting through one's weapons" would either be a remake of Demonic Sword Gram or Kirito utilizing his Arms Blast (outside system skill). If such a remade effect was implemented into Excaliber, then anyone with a high enough One-Handed Sword Skill should easily invoke that effect.
However, I can't say much about the Sugou vs Kirito fight, since Sugou lost his administrative powers (and thus his "cheated" levels) when Kirito set Sugou's authoritative status to Level 1 (probably the level of a standard player. As for what the authoritative level of an admin/GM, I have no idea).
And... weapons do not carry an elemental element. As far as I know, only Sword Skills do.