ok thanks for your reply it is confusing, I think I know how I managed a base damage of 9999, if you have a hp plus eqquiped during the earlier levels of the character then he benefits from increased growth eg.
level 30 character
hp 3000 + level 1 hp plus = hp 3300
gets to level 31 his hp lets say normally goes up 180 so now
hp 3180 but if hp plus equipped then rise is 198 taking base to 3198 then adds 10% still so 3498 but if the materia was removed the character still has higher hp then normal. I am sure this is how I managed 9999 without hp plus.
I agree with you on the attack % etc. but not sure about the critical hit chance when above 100%, if I equip a 255% weapon then in theory every hit should be a critical hit but isn't, however it does make deathblow always hit critical.
