Welcome to Tnet. No, the chain is not original official issue and I don’t think the dart/stake/dagger charm is related to the tag.
During World War II, the U.S. Army initially issued dog tags with shoelace-like cotton cords or fabric lanyards (up until 1940), and then with linked ‘curb’ style metal chains which were standardised with double J-clasps (aka ‘sister-hooks’) in 1943. Like this:
This setup used a linked chain with two twin-hook catches that required both hands to open and clamp onto the tag holes, suspending one tag lower than the other. There were two tags such that, in the event of casualty, one remained with the body for permanent ID and the other was collected for reporting and administration purposes.
In 1944, they switched to a beaded ball chain.
I'm, ignoring the employee pin, but I assume you know it's the same person as for the dog tag.