Again to fix this solution something like 0.1% drop rate increase per FATE completion will increase the chance. This being applied for the quest meaning 0.1% increases on all area's rather than just that one areas atma drop (easier for programmers) 10 FATE = 1% increase, 100 FATE = 10% increase, 1000 FATE = 100% increase. This way if you put in time and complete 1000 FATE you're bound to get this part of the zodiac weapon completed. Downside for this it's going to need another data being stored on serverside so it could cause extra process.

Still there are much harder task after this so once this part's done everyones just going to repeat the same for the next, and next, and so on.