Tar-Calmacil was the Quenya name of 18th ruler of Númenor, also known as Ad. Ar-Belzagar (UT/222). This name seems to be a compound of cala “light” and macil “sword”.
Quenya
Calmacil
light-sword
calmacil
masculine name. *Sword of Light, Shining Sword
Calmacil masc. name, *"Light-sword" or possibly (if haplology of *Calmamacil*) "Lamp-sword" (Appendix A). Cf. cálë, cala, calma, macil**.