Jim, I missed the glue part. So long as the glue itself holds, you should be fine. In essence that makes the cord purely decorative, sorry if I missed that in an earlier post.
With that said, the strength of the cord is largely irrelevant to the issue of stretching. Rock climbing rope is more than strong enough to hold a pendant, but would do a poor job as the rope is designed to be elastic. The worry is how much a cord will stretch, not how much weight it will bear before breaking. Most cords designed to hold a load are designed to stretch some, elasticity reduces the shock to the rope and the load.
Another idea if you want a more "pure" cord look, but don't want a decorative knot on top. Find some strong thread the same color as the cord and stitch the cord together. Since the pendant is actually held by the glue, and not by tension, this should be sufficient.