brittle, fragile, easy to beat, sentimental, susceptible
脆 centers on a lack of toughness or resilience: something that is brittle, fragile, or easily broken. The extended senses of being sentimental or susceptible describe emotional fragility, while 'easy to beat' applies the same idea to a weak opponent.
脆 combines the flesh component ⺼ with 危, which likely contributes both sound and the idea of danger or precariousness, suggesting flesh that is easily damaged.
The flesh radical ⺼ beside 危 (danger) paints a picture of meat that is in danger of falling apart—brittle and fragile.
For ゼイ, imagine a brittle twig snapping with a sharp 'zay' sound: zay -> ゼイ, and the fragile piece breaks.
weak; frail; fragile
brittle; fragile; weak; frail
zero-day vulnerability
hydrogen embrittlement
quickly (succumb, collapse, etc.); easily; without resistance (despite hopes to the contrary)
embrittlement
fragile state
vulnerability; weakness; fragility
brittleness