disease of the eyes, crime, fault
眚 centers on a flaw or defect, originally tied to eye disease, and extends to moral faults or crimes as a kind of blemish on a person.
眚 combines 生 (life, birth) with 目 (eye), likely suggesting an eye affliction that is present from birth or a natural defect. The extension to crime or fault is a metaphorical use of a blemish.
The top 生 (life) over 目 (eye) suggests a lifelong eye problem. Think of a visible flaw in the eye that represents any kind of fault or crime.
For セイ, imagine saying 'say' to point out a fault: 'Say what's wrong with your eye!' The word 'say' cues セイ while you point at the eye defect.
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