Weapons do pathetic damage against Ruby Weapon. Omnislash did about 200 damage with each hit after I had given Cloud like 6-10 Hero Drinks. If you don't want to use KotR, Cait Sith's limit break (for instant win) or Lucky 7's, I'd suggest using Hades (to stun Ruby) and Bahamut Zero, and then miming them. Even that will take a long time, and if watching KotR will get you bored, watching these summons 799,999 / 9999 = 80.007, i.e. 81 times, will be plain horrible.