what's wrong with my syntax in this iRule?

Can't have iRule events nested inside other events.

when CLIENTSSL_HANDSHAKE {
    if { [IP::addr [IP::client_addr] equals 10.10.10.10] } {
        log local0. "[TCP::client_port] :: RSA Session-ID:[SSL::sessionid] Master-Key:[SSL::sessionsecret]"
    }
}

when SERVERSSL_HANDSHAKE {
    if { [IP::addr [IP::client_addr] equals 10.10.10.10] } {
        log local0. "[TCP::client_port] :: RSA Session-ID:[SSL::sessionid] Master-Key:[SSL::sessionsecret]"
    }
}

Just do this in the server side event to see what the client IP is:

when SERVERSSL_HANDSHAKE {
    log local0. "client IP: [IP::client_addr]"
    if { [IP::addr [IP::client_addr] equals 10.10.10.10] } {
        log local0. "[TCP::client_port] :: RSA Session-ID:[SSL::sessionid] Master-Key:[SSL::sessionsecret]"
    }
}