Obtaining higher combos will unlock more powerful weapons. I was able to unlock the aegis charm 4 which raises your defense up by 80%. I was also about to obtain the Royal Flag (50% range attack & 20% Attack Power) and Royal Crown (Critical 50%).

The trick is to use those cursed items to weaken your character so you dont kill everyone in one hit. Each character has a level where you can rack up a huge combo. I got those items for Imphyy when I first reach a 9800 combo!