to reply to the things you said earlier that i didnt read...
the attack gilgamesh does that only does 1 is "excalipoor", a mockery of excalibur. in ffV, when you fight gilgamesh, he says he found the legendary sword, excalibur. (but it only does 1 when he uses it.) he gets sucked into the cleft of dimension by his frustrated superior, x-death. you find the excalibur, only its called "excalipoor", and although it has the same attack power of excalibur, it will only do 1 damage in battle.
his other attack , "excalibur" does moderate damage. (i guess. gilg hardly appears for me...)
as for the theory of him being sucked into ffVIII, its only a theory. (therefore, its not true
) square just likes too re-use things in ffs, like you said
unfortunately, it doesnt stop people from creating wacky theories...