First time defeating this enemy on PC, had to resort to Dazers and Hades to cheese Ruby Weapon as it will counter with Ultima upon summoning Knights of the Round. Ruby Weapon is the hardest superboss in FF7, more so than Emerald as it has very high defense and will remove party members if you initiate battle with a full party. Equipping a few mastered Summon Materia and Counter-Command and Mime Materia on each party member will cause Ruby Weapon to go down easily. Megalixirs and Hero Drinks also increase survivability as well. By using Knights of the Round about 7-8 times with some 4X attacks it will go down, though it can get pretty hands off when the longest summon is repeated so many times. ... https://www.youtube.com/watch?v=IoYchHZrHoU