What I like the most about her design is how it's not just amazing on its own but it is also nuanced to convey a stark contrast between her and other characters. Specifically, I find it adorable how different Squigly and Leviathan are to Filia and Samson. The former duo is symbiotic, well-rehearsed and totally trusting which is why their movements are so elegant and refined and they both appear to do an equal share of the work (plus they've had more practice) whereas the latter are 'rough and ready' but have a deliberately messy fighting style where it's as though Samson is fighting by himself and is dragging Filia along. This is actually in the development notes and I find this kind of subtlety to be appealing because it characterises internal thought as well as external aesthetic.