Appropriate compliments to a CISSP:
"Nice work."
"Good looking pin on your lapel."
"Great shoes!" [How do you identify an infosec extrovert? He is staring at your shoes instead of his own when he talks to you.]
As for complementing a CISSP infosec certification, instead of rummaging through the many other infosec and cyber certs others have listed, which may supplement a CISSP but not complement it, I strongly recommend every CISSP consider two that truly broaden the utility of your infosec expertise:
- Project Management Professional (PMP) from PMI;
- Certified System Engineering Professional (CSEP) from INCOSE.
Both of those will add to your skill set to actually implement the great infosec ideas you have.