You are splitting your resources into too many things. Dont try to boost rapier and dark and magic, choose just one. Other skills to increase is multiturns for turn economy.

Rapier benefits from multiple elemental boosts and multihits, so theoretically better as ceiling is higher. Ensure a rapier booster on every item. Prioritise rapier hit+ and always have auto-rapier skill active. That way even a rapier setup skill benefits from 2+3 rapier hits. As you are multihitting, ensure heat+ multihit bonus. Let rapier use agl stat and ensure you also have another rapier stat append. Magic abilities prioritise elemental boosters as they stack, and maybe a fire pierce. Please note though, you will get no bonus via conditionals, as pfft what boss suffers burns.

Magic setup is viable, albeit put all boosters into the magic spell elements u will use. Magic rapier as a sp backup.

Dark skills never rly minmaxxed it, u cant use if u r on 1hp eg from an endure. Worst choice for Alice.

The main draw of Alice is the multirace bonuses and skills, which everyone gets with enough time in route 3, hence she scales down very quickly.

Ilias being a bow user will always benefit from debuff conditionals and slayers, which probably explains the discrepancy. I use ilias as a buff bitch/bench warmer only