There doesn't seem much worth putting on artifact rings and amulets compared to building dex rings and grace/con amulets. Both song of Elbereth and song of Trees look thematically appropriate. Heck most of them look viable to me, is there a reason they were left off? I'd do a Feanor jeweller with lesser jewel of Elbereth and a pt of song at the 1st forge if I could. I can't justify it on an amulet because a singer smith is liable to replace it with an amulet of grace anyway.