The most suitable tool to identify potential security risks associated with Lightning Web Components is the Health Check. Health Check allows Salesforce administrators to evaluate and monitor the security posture of their Salesforce org by comparing its settings against Salesforce's recommended security baseline. This feature provides visibility into settings like session security, password policies, and more, which can directly impact the security of custom apps using Lightning Web Components.

Health Check:

Salesforce Health Check examines various security settings in your Salesforce org and provides a score based on how closely your settings align with Salesforce's recommended security baseline.

By using this tool, administrators can identify vulnerabilities and see specific actions to remediate any security gaps found within the org.

Health Check is especially relevant when evaluating new custom applications and components since it can highlight areas that require tightening security to meet organizational standards.

Other options listed:

Master Encryption Keys is relevant for managing encryption but not directly for identifying security risks.

Salesforce Optimizer is used for overall performance and usage insights and doesn’t specifically focus on security assessments.

Self-signed Certificates are primarily used for secure communications and do not serve as a tool for security risk assessment.

Therefore, Health Check is the best tool to help the administrator expose potential security risks within the custom Lightning Web Components.