This heroic trio comes from Marion Zimmer Bradley's "Darkover" saga, "The Sword of Aldones," in which the characters must wield a godlike flaming sword against a coalition of villains. It was created for a fan magazine, "Moon Phases," which flourished in the heyday (what's a "heyday" anyway?) of Darkover's popularity in the mid-1980s. I used to squander my time creating illustrations for these 'zines for little or no money, while other artists were busy building real illustration careers.
"Moon Phases" cover is ink on illustration board, 8" x 10", fall 1983, published 1985.