I also liked the use of piercings/jewelry. I can imagine that those would be used to signify rank or enemy kills.
I don't think they'd do that. Klingons have never worn rank insignia of any kind, since they can be trusted to be exactly the rank they say they are - it would be grossly dishonorable to lie about your rank or how many enemies you killed.
A Klingon might wear things like this as pure decoration, but not to signify anything specific. Their word is good enough.