warn, warning
儆 centers on giving a cautionary notice to prevent harm or error: warning someone or issuing a warning.
儆 combines 亻 (person) with 敬, which likely contributes both sound and the idea of respect or caution, suggesting a person giving a respectful warning.
A person 亻 beside 敬 (respect/caution) stands ready to warn others: 儆 is a person issuing a warning.
For ケイ, imagine a person giving a warning by holding up a large letter K: K -> ケイ, and the K stands for 'caution'.